At midnight in a cemetery, the GRX racecar engine is unearthed. The following day Spritle and Chim are trapped inside a truck. It takes them to Oriana Flub's house, where Chim Chim is tied to a motorized go-cart. When the chimp comes to a stop, one of Oriana's men sprays a "formula" at him. As he takes off again, Oriana announces that "they'll win the Grand Prix of the Orient." At the track, a new racecar comes on the scene. Pops recognizes the sound of its engine. High in the stands, Oriana and her right-hand man, Omar watch while a thug sprays the driver of the mysterious car with the formula. At Oriana's house, Pops accuses her of stealing the engine ""out of the tomb of Bent Cranium,"" the engine's inventor. Pops adds that five test drivers and Cranium died because of the GRX. Oriana knocks him out with "sleeper gas." Meanwhile, Speed in the Mach 5, along with Trixie and Sparky, follows a flatbed truck carrying the GRX race car.

The Masked Racer takes Speed to his house. He is really Speed's older brother, Rex Racer. Speed awakens. A quick look around the room finds the Masked Racer in the shower and his mask on the chair. Speed tries on the mask and is knocked unconscious by an intruder. Outside the house, Trixie arrives and sees "the Masked Racer" seated between two men. She asks if they've seen Speed. They drive away with Spritle and Chim Chim hiding in the trunk. At Wiley's mansion, Speed's mask is removed. Fixer walks in with Spritle and Chim Chim as prisoners; Chim Chim escapes and finds Trixie. Speed and Spritle are tied up. Ultimately, the Masked Racer rescues them. On race day, the Racers watch the event on television. At the track, Spritle overhears Mr. Fixer give his thugs the order to fill the Masked Racer's radiator with gasoline. Spritle and Chim Chim switch the drums so that an Alpha Team member's car explodes. The Masked Racer's car blows a tire, but he continues on three wheels.

Speed and Trixie drive to the shipyard where the Masked Racer's car is being unloaded for the upcoming Trans Country Race. Trixie hints to Speed that he should enter the race. He hesitantly agrees. At the Racer homestead, while watching TV, Pops learns that Speed has entered the race. He "blows a gasket" and reminisces about the loss of his oldest son, Rex, who joined a race without his permission. At the brink of victory, Rex crashed the car Pops had built. Although Rex was uninjured, Pops refused to let him drive again, citing Rex's lack of experience. Consequently, Rex vowed never to return home. Meanwhile, the Alpha Team is holding a secret conference to plot a way to win the race. Mr. Wiley tells Mr. Fixer and Alpha Team driver Zoomer Slick to "pull the dirty trick first." Determined to beat the Masked Racer, Speed sneaks out in the middle of the night and goes to the track. Despite heavy rains he is not deterred. The Masked Racer warns him to stay out of the race.

Speed realizes that Cumulus isn't going to keep missing forever. He uses the autojacks and beats feet out of there with Cumulus in hot pursuit. With a clever ruse, Speed manages to destroy the Mesmo gun with the homing robot. Cumulus takes off with Speed chasing. The Cumulus 5 takes flight. Overhead, Inspector Detector is watching the fun below. Spritle and Chim Chim have stowed aboard. The Cumulus 5 dives into the water. Speed follows. He uses his nightshades to see in the dark. Cumulus heads into an underground cave. Deep in the cave, a steel door slams shut behind Cumulus and Speed crashes into it. He has less than half a tank of oxygen left. Inspector Detector is searching for the Mach Five on a rescue vessel. Spritle and Chim Chim have stowed aboard again. The inspector orders his men to catch the two and lock them in a cabin. After eluding the police, Spritle and Chim Chim don a diving suit. Chim Chim is the head, so when they meet the inspector, he sees through the disguise. Spr

Satisfied that the Mach 5 is forever submerged in Lake Icy Chill, the Mammoth Car drivers resume the race. Through his telescanner, Speed sees them leave as he reaches soil. Trixie sends a message in the homing robot to Inspector Detector. The stolen gold is aboard the Mammoth Car. From his plane, Cruncher Block sees the Mach 5 on the road. At the refueling station, Speed and Trixie are fired at. Escaping into a mining tunnel, they jump on top of a speeding trolley car, which crashes. Meanwhile, at the refueling station, Spritle and Chim Chim sneak out of Cruncher's plane. They, too, escape into the tunnel, which turns out to be Cruncher's headquarters. There, Speed and Trixie are tied to a trolley loaded with three tons of dynamite. Ultimately, Racer X arrives and saves them. At the next checkpoint, the Inspector searches the Mammoth Car. Again, he finds nothing. Speed reaches the checkpoint; Spritle and Chim Chim slip out to hide in the Mammoth Car.

While out on a practice race, Speed is almost run off the track by a mysterious black car. Later that night, the black car gains on an automobile whose driver recognizes it as the X3. Before causing the auto to crash, the black car broadcasts, "Melange still races." A second car is also caused to crash. The next day, Inspector Detector asks for Speed's help. While Spritle and Chim Chim hide in the Mach 5's trunk with a tape recorder, a chase ensues, but the X3 outdistances Speed. Spritle produces a tape recording of the X3's message. Pops explains that the recent victims were the coaches of the Three Roses Club race team, the expected victors of the Danger Pass Race. However, they were worried Slash Market driving car number X3, the Melange, might beat them. Mysteriously, the Melange crashed. Pops recalls that Slash had two children – Slash Jr. and Lilly. The Inspector, Speed, and Trixie pay the siblings a visit and learn that they know nothing.

Speed resumes the Sword Mountain Race, neck and neck with Duggery. Ace and his gang approach from the opposite direction. Speed swerves off the road and uses his rotary saws to cut a path through the overgrown terrain. Trixie creates a temporary distraction, bombing the gang with smoke flares from her plane. At a cross-road, Duggery decides to take a "shortcut." Speed knows that the road leads to a dangerous volcano and sets out to rescue him. Meanwhile, Ace and his gang fire at Trixie. The plane plummets but Trixie escapes. At the edge of the volcano, Duggery is thrown from his car, and left dangling from a rock. Speed also ends up on a rock shelf after trying to rescue his competitor. They manage to reach safety but find that the gang surrounds the Mach 5, with Trixie taken hostage. Spritle and Chim Chim, who have hidden in the Mach 5's trunk, throw rocks at the gang while Speed, Duggery, and Trixie fight them off. Ace takes off in the Mach 5. Speed follows in hot pursuit.

Trixie wins the position of Speed's assistant in the No Limit World Race. Before the race begins Inspector Detector and his officials search each entry looking for $50 million in stolen gold bars. The Mammoth Car enters the track. Cruncher Block gives the Inspector a tour, yielding no trace of the gold. The race begins. The Mammoth Car forces everyone off the road. Speed is suspicious. To discover the Mammoth Car's secret, he equips the homing robot with X-ray film able to penetrate metal. Unfortunately, it's shot down and returns broken. The Mammoth Car catches up to Speed and forces the Mach 5 off the road. A ramp is lowered and a squad of motorcyclists descends onto the track. Racer X appears and spritzes oil on the road, causing the cyclists to crash. Meanwhile, at the airport, Spritle and Chim Chim stow away aboard Cruncher Block's plane. Back on the track, the Mach 5 and the Mammoth Car collide and both veer off the road toward a forest.

Speed has passed out behind the wheel of the GRX. Eventually, the car comes to a half at the edge of an aqueduct. Spritle and Chim Chim drag Speed out of the racecar. One of Oriana's thugs gets in the GRX and drives away. At the Racer homestead Pops sets out to ""cure"" Speed of his delusions. Later at the racetrack, the final trials for the Oriental Grand Prix are about to begin. Oriana's thug squirts the formula at Louis Towcar so that he can ""stand the speed of the GRX."" Further, he warns the driver that if he drinks water while he is driving, ""you'll get so scared, you'll lose control of the car and smash into smithereens. The race begins. Towcar tries to quench his insatiable thirst. A chemical reaction takes effect and Towcar passes out. Speed autojacks over the GRX, which blows up. Later, in her helicopter, Oriana asks Speed to drive the GRX in the upcoming race. Speed gets into the repaired GRX racecar. The thug gives him the formula. He takes off. Upon spotting Spee

The scene is one of the most secret secret places in the world, the secret National Science Institute. Professor Tower leaves late that night. He seems in very good spirits. The guards deduce that the professor has finished his latest invention, a new powerful ray called the Mesmo. Just then, the Mach Five approaches at high speed and jumps the gate. The alarm sounds, but not before the armed burglar can steal some important documents. The next day, at the Racer home, Spritle is working on a model of the Mach Five in the garage. Speed wakes up after a late night out. He turns on the television, and the news is reporting the burglary at the secret National Science Institute. Spritle takes his car out for a test drive. He pushes a button marked ""A"" on the steering wheel. The jacks extend on only one side. He then tries the other button marked ""B"" and only some of the grip tires deploy. A wheel comes off and the car crashes. Spritle lands at the feet of a cop who threatens to give him a t

Speed figgers that the statues must be under some sort of remote control. Then, the statues fire pistols at him. When the smoke clears, Speed is okay, but then the assassins drop in. Speed fends off their attack, but he's met by Gat Gunsel, the leader of the local division of assassins. The organization is world-wide. Speed is ordered to walk to a statue. Behind the statue is a secret entrance to the assassins' headquarters. In a cell, the diplomats from the sightseeing boat are locked up. Speed watches the assassins demonstrate their skills. One shoots the pips out of a five of spades. Others walk through a fire; another cracks a rock with a karate chop; and another walks on the ceiling. Then the assassins show off their driving skills. The cars they drive are specialized weapons. Speed is taken to the leader of the entire assassin organization, Professor Anarchy. Speed is offered a job with the gang. Speed refuses. Professor Anarchy is going to let Speed be his 2,708th kill, a great

After winning a practice race, Speed Racer is offered a position on a team set to race in the Grand Prix. The company who employs his father, Pops Racer, a top engineer, owns the team. However, Speed declines because Pops doesn't want him to become a pro. Meanwhile, Pops quits when his plans to improve the Mach 5 are rejected. While Pops and Speed are driving home, a gang of motorcycle racers steals their plans. Trixie, in her helicopter, runs the gang off the road and the plans are recovered. Back at the cyclist headquarters, bad guy Acey Ducey shows up and offers to get the plans for "5,000 clams." He confronts Pops but leaves empty-handed as Pops has hidden the designs on the Mach 5's windshield using invisible ink. Deciding to sell the Mach 5 so Pops can rebuild the engine, Speed visits Sparky, who suggests that Speed enter the Sword Mountain Race for a $5,000 prize. While Speed takes the Mach 5 out for a road test, "dirty driver" Duggery rams the car, causing it to blow a tire.

It is the second day of the Big Alpine Race and no one has been able to cross the chasm except for Racer X. In a nearby lodge, Trixie, Sparky, Spritle, and Chim Chim await the passage of the storm. Two drivers deliver the news of what happened at the pass. Trixie and the gang leave in her helicopter to rescue Speed. The next morning, Speed regains consciousness, discovering that he is unable to see. Somehow, he finds the Mach 5 and starts its engine. Snake Oiler cruises by "on his way to victory." Using his acute sense of hearing, Speed follows the sound of Racer X's car, which leads him back onto the racecourse. However, the Mach 5's wheels get stuck and Racer X leaves him behind. What goes around, comes around: Racer X crashes, his legs apparently broken. Speed finds him and, together as a team in the Mach 5, they plan to overtake Snake and win the race.

Speed is in the exotic and mysterious city of Ambrosia, high in the Mystic Mountains on Lake Ripplelapps. It is the start of the Mystic Grand Prix. Piston Powers holds the pole position. Racer X is also in the race. Prince Snowier and Princess Gracious preside over the race, and Princess Gracious will signal the start. A sniper has the princess in his sights. A reflection from one of the cars in the race distracts the sniper and he misses. He runs and Speed chases him in his supercharged formula one. The two wrestle on the roof of a building. Speed prevails and the gunman falls to his doom. A secret meeting is being held in one of the suites on a train leaving Ambrosia. One of the men has the mirror that was used to distract the sniper. Among those suspected of using the mirror are Bearcat Stutz of the country of Pong Ping and Tailgate Jones of South Bosawania. The three most likely candidates are Rusty Muffle, Tailgate Crumple and Speed Racer. Avalonia is the next stop, where the haza

This is a sequel to the 'The Most Dangerous Race' and takes place one year after the events related in that episode. It involves a group of international spies tricking the Car Acrobatic Team and Speed Racer into having a race. The race is to lure out Racer X who the spies have figured out is Speed's older brother. In addition the spies have planted bombs in the cars of the Car Acrobatic Team to blow up Speed. In the end it is the spies who get blown up. Also Speed figures out that Racer X is his brother Rex and asks him. Racer X knocks out Speed, removes his mask, and vows to stop being a racer and become a full time secret agent.

With Lilly passed out at the wheel, Speed realizes that Slash Jr. is driving the Melange via remote control. Unable to overtake it, Speed pulls over and discovers that Trixie has stowed away. Up ahead, the Melange approaches the Three Roses Club cars. Trixie sends a message in the homing robot that car number 3 is really the X3 Melange. Meanwhile, the Melange causes two of the Club cars to crash. Speed takes a shortcut over the mountain. He intersects the remaining Club car and the Melange car. Slash Jr. follows overhead, shooting at Speed. The sound of the gunfire, coupled with the thunder of the helicopter, causes an avalanche. Speed and Trixie climb to safety. Meanwhile, Inspector Detector, Pops, and a convoy of police officials head out to capture Slash Jr. Speed catches up to the driverless Melange. While Trixie takes over the Mach 5's steering wheel, Speed jumps into the Melange. Unfortunately, Speed is too late, and the Melange collides with the third Club car.

While the Flathill Army soldiers set the Mach 5 aflame, Speed attacks one of the rebels. The General announces that he ordered Ali Ben Schemer, his cousin, to blow up his son's racecar because they need his help in the revolution. When Kim notes that his special brakes can never be repaired, Schemer suggests that Kim and Speed race without brakes. The next morning, Schemer gives them a sack lunch and the race begins. He then takes Trixie, Spritle, and the General prisoner. Chim Chim rescues Spritle and they escape on a camel. Meanwhile, as the Black Tiger and the Mach 5 race through the desert, the sack "lunches" open revealing deadly scorpions. Kim realizes what Schemer is up to. The scorpions are smashed; the race resumes. Later, members of the Flathill Government Army, who are after the rebels, rescue Spritle and Chim Chim. Back on the racecourse, the Black Tiger is devoured by quicksand. Kim, Speed, and the Mach 5 almost meet the same fate.

At the base of a tall building, Speed and company watch Twinkle Banks, star of the Universal Circus, dive off the top. Then, at the circus, they watch Twinkle drive a racecar and perform daredevil stunts. She worries about maintaining the car's momentum and faints. Speed rescues Twinkle. While the girl daredevil rests in bed, a clown (her father) tells Speed that because of a money shortage, he's having difficulty keeping the track in good repair. Speed makes a donation. Later, Speed and Trixie learn on the radio that Twinkle will drive a car, balanced on two ropes, over Niagara Falls. Because of the strong winds Speed and Trixie try to stop Twinkle. Meanwhile, Cornpone Brush, who financed the stunt, tells the clown that Twinkle will perform regardless of the hazardous weather. When Speed and Trixie arrive, Twinkle is already making her way across the Falls. Away from the crowd, Brush reads an old map. It identifies a secret cave in back of the Falls that leads to treasure.

A bank robber escapes from prison and forces Speed to take him to where he hid the money. Other gangsters try to get the money. The convict dies, but asks that his eyes be given to his daughter, who is blind.

The episode opens in Africa with the scene of a lion chasing a leopard. As the two fight, a huge gorilla enters. Broken shackles dangle from the gorilla's wrists. Speed is flying to Africa. Professor Robert Carnivoré is sitting next to Speed on the plane. He relates the story of a huge monster that lives near the mountain they're flying over. Speed will be participating in the Trans-Africa Grand Prix, a race which crosses the continent of Africa. He checked out the course and is on his way to Nairobi where the race will start. The pilot and co-pilot point weapons at the professor and Speed. They are exiles from the nation of Bangdabongo. Carnivoré is also an ex-pat from Bangdabongo. The men need the professor's help to liberate their country which was taken over 20 years before. The men and the professor get parachutes to jump out safely. Speed is tied up. As the plane plummets earthward, Speed snaps the ropes. He dons a parachute and jumps out at the last moment. Down on the ground, S

Speed is recuperating in a room at the National Hospital. The President is also in the hospital in room 1. Of course, Speed is in room 5. Rudolph Elegantor is there to pay his compliments on behalf of Vice President Duper, who looks a little like Hitler without a mustache. Speed is invited to the Vice President's home. Racer X also pays a visit, but when he hears of the invitation to Duper's home, he changes. Could he be a secret agent? Speed visits the Vice President, who lives underground. Speed is locked in a room to wait for the Vice President. Speed is escorted to see the Vice President, but on the way, a gun is pulled on him. Speed wrestles the gun away, but his advantage is short-lived. He gets hit over the head. The Mach Five leaves with someone disguised as Speed. Racer X arrives at Duper's home and is told Speed left. He takes off in search of his long-lost brother. Meanwhile, Speed is really in the trunk of the Mach Five, still unconscious. He's put in the car and the Mach F

A man uses small cars which allow him to control real cars that he then melts down and uses to build a forest complete with robotic animals. He is destroying cars because his son was crippled by a hit and run driver, but it is reveled that his son can really walk and was kept in the wheelchair by his father.

Speed, Trixie, Spritle and Chim Chim are flying to Hong Kong for the Hong Kong International Race. Speed notices a woman passenger acting mysteriously as she plays with her compact. The compact is actually a sophisticated weapon which fires a poisoned dart at a another passenger sitting further back in the plane. As Speed tries to question the woman, she collapses because she has been hit with a similar poisoned dart. We see the stewardess in the back of the plane with an evil smirk. Chim Chim hands Speed an invitation to one of Hong Kong's floating restaurants. The invitation fell out of the woman's purse. Speed is accosted by a group of reporters as he gets off the plane, but they split immediately when Princess Petal's plane lands. She is a mysterious princess from the Kingdom of Blossombow in the Middle East. Speed puts his foot in it when he admires the princess for her elegance. An assassin has her sights on the princess, but she is restrained by the stewardess who cautions her t

Vavoom Motor Co. is trying to build a supersonic car, which Speed is testing. Agents from Forthebird Motor Co. sabotage the car, and blame Speed for the accident. They demand a new test driver, but Speed enters their driving tests, and proves again that he is the best driver. Agents from Forthebird Motors put a bomb on the finish line to destroy the car, but Spritle overhears them, and warns Speed.

A madman in a weird mask wires the Mach Five into a bomb to use it and Speed to steal art treasures.