An old tramp, Trundle, looking for odd jobs, fascinates Sonny with tales of adventure. However, Matt Hammond believes the stories are figments of Trundle's imagination and considers it a bad association for Sonny. Trouble begins when the old swagman gives Sonny an expensive antique watch as a parting gift. Matt discovers the gift, asks the police to trace the owner… and discovers the Swagman's secret. Trundle turns out to be Miles Vincent Archer, the wealthy chairman of a vast corporation.

A mysterious disease threatens to wipe out all animals in Waratah National Park, and evidence points to Skippy as the carrier. Sonny is heartbroken at the possibility of losing Skippy, and disappears into the bush with the kangaroo. There he comes across a poacher, and Dr. Steiner discovers that the poacher's dogs are the actual carriers of the disease.

A young runaway holds Mark and Jerry at gunpoint demanding to be flown out of the park. Skippy leaps to the rescue and the boy flees on foot only to go over a ravine. Jerry risks his life the boy who would rather fall to his death than accept help.

Matt Hammond's boss and a government Senator decide to sack him after it appears that Matt has run their car off the road and threatened them. It transpires that Dr. Stark has hired an actor to impersonate Matt Hammond in order to discredit him, but the whole scheme backfires and Dr. Stark has to honour the promise of a $10,000 donation to Waratah National Park.

Sonny's birthday wish comes true — a ride in the helicopter, but not the way he expects. While flying over Sydney, Flight Ranger Jerry King collapses, leaving Sonny alone with the controls. To save their lives, Matt tries to use a tranquilizer gun to deliver the medicine to Jerry while flying alongside. When that fails, Sonny must be talked through landing the helicopter on his own.

Sonny, helped by Skippy, takes a job with a team of sheep shearers, not knowing they are rustlers, to earn money to buy a birthday present for his father. His absence from home puts Matt Hammond on the track of the three strange characters who have developed a variation of sheep rustling — they only take the wool!

Sonny makes a new friend Lisa, a young ballerina. Together they find an aged Botanist who has been missing in Waratah National Park and, with Skippy's help, bring about his rescue.

A diamond thief loses a valuable necklace while on the run from the police in the park. The thief sees Skippy find it and places it in her pouch and follows her back to the ranger station where the Hammonds are busy building a parade float. The thief stows away on the float and a dramatic fight breaks out when he tries to recover the necklace as the float makes its way through the streets of Sydney.

Sonny and Skippy discover the hidden entrance to a remote valley, thought to be inaccessible and uninhabited. There Sonny makes friends with an old Aboriginal living alone, whose tribe has long since migrated to other parts of the country. One day Sonny finds Tara weak and in a semi-coma — he believes he has been visited by a 'death spirit' and is going to die.

A research scientist who is to study marsupial wildlife at Waratah National Park turns out to be an attractive young woman. Her methods anger Chief Ranger Matt Hammond and she has to be rescued from serious trouble on a koala trapping foray into the lonely bush.

Sonny and Skippy become guides for foreign children stopping at Waratah National Park while touring Australia.

While Park Ranger Matt Hammond and Clancy are busy fighting a bush fire, Jerry makes a gallant attempt to win the Bondi Surf Championship — despite having just sustained serious injuries while rescuing a surfer girl in distress.

An invasion of sports cars threatens the life of protected fauna in Waratah National Park, but when Matt leads a rescue squad to save the life of a driver pinned under his car in a serious accident, the rally organisers gratefully decide on another venue.

Dr. Alexander Stark is determined to have Skippy for his private zoo. When Matt Hammond refuses to sell at any price, Stark has two of his henchman steal the kangaroo and she begins a tense series of adventures to find her way home.

Aboriginal warriors come to Waratah National Park to claim a run-away tribal girl. Head Ranger Matt Hammond defies their spears, convinces the elder that the girl's great talent for singing can help bring white and black people closer together.

Matt locates Mr Judd, the businessman whose life Tara saved, hoping he will help bring in people from Tara's tribe who will have the ability to free Tara from death.

An aging film star attempts a comeback on a new movie being filmed in the National Park. When Skippy inserts herself into a scene, a new star is born — much to the annoyance of the leading man who tries to have Skippy 'taken care of'.

Skippy stumbles on a secret boxing training camp illegally set up in Waratah National Park. A young champion, Rocky Miller, takes a forbidden joy ride in the helicopter with Jerry King, and a forced landing has surprise results.

While trying to do a good deed for Theresa Fiorini, Mark accidentally releases her father's cows from their paddock. Mark tries to impress the pretty girl by learning Italian but his language skills prove more useful with her father.

While visiting a travelling carnival, Sonny meets Carrie Mason, a girl who wants nothing in the world but to be a clown. Skippy falls in love with a wooden kangaroo on the carnival's merry-go-round. Carrie finds she has much in common with Skippy when they both decide to run away and join the carnival.

Sonny, Mark and Jerry investigate an expensive game fishing cruiser with three men aboard after Skippy and Sonny came across men trapping animals in the bush at night. Swimming out to the cruiser, Jerry overhears a conversation which indicates the men are stealing koalas for Dr. Stark's private zoo.

Skin-diving geologists discover aluvial gold on a reef at Seal Rocks, in the mouth of the Flinders River. Thieves move in armed with deadly spear guns, and once again Matt, Sonny and Skippy are there to stop them.

Matt Hammond is faced with a human problem when one of his rangers moves to a new nature reserve up north, taking his wife and sons but leaving his daughter Clancy, who has exams pending, to board with the Hammonds. Clancy is in trouble from the moment she comes to stay, and she gets the idea she is not wanted and runs away.

Overhearing the doctor tell Matt that he ought to marry again, Sonny tries his hand at matchmaking when he answers lonely hearts advertisements in Matt's name — and has to face the consequences.

Matt's discovery of an abandoned sports car leads him into a violent encounter with the driver, a delusional war veteran who then takes Sonny hostage before stealing an airplane.