U.N.C.L.E. and Thrush agents compete to gain possession of a mind-reading device created by a magician who has been murdered by Thrush.

When secret ""File 40"" documents turn up outside headquarters, Waverly assigns Solo and Illya to find out if George Donnell is a double agent. Carla Drosten is too anxious to accuse Donnell and Solo must use special ""Waverly rings"" to try and expose the real double agent.

THRUSH agent Elom tries to kidnap a geologist who has developed an earthquake activating machine, but mistakes debt-ridden salesman Buzz Conway for the scientist. Solo and Illya let THRUSH go on thinking Conway is the scientist, while Elom lets his attraction for THRUSH agent Narcissus Darling interfere with his judgment. Conway is captured, and Solo and Illya must rescue him and find the machine.

Solo and Illya devise a clever scheme to discredit a Balkan intelligence chief (Werner Klemperer) with a bogus secret gas. With the help of a bankrupt exterminator (William Shatner) and his wife, Illya poses as a fellow countryman and exploits the paranoia of the chief and his bumbling assistant (Leonard Nimoy).

When a minor European leader is assassinated, Solo steals a medallion from his body containing a microdot listing the THRUSH agents in the country, but must elude the secret police and outwit intelligence agent Satine (Ricardo Montalban), who also wants the medal. Teacher and tour guide Sara Taub (June Lockhart) and her high school students are used by Solo to try and sneak the medal over the border.

U.N.C.L.E. must transport captured THRUSH official Egon Stryker (Ralph Taeger) from New York to Washington with THRUSH rescuing him. While Waverly takes a decoy along one route, Solo and Illya take the real Stryker. Or is it ? But in a mixup, Fran Parsons (Joanna Moore),a secretary on her lunch hour, gets handcuffed to Stryker and has to go along.

Solo and Illya board the Adriatic Express train on New Year's Eve to intercept Madame Nemirovitch, a THRUSH agent who is carrying a chemical that is capable of stopping the reproductive process. Eva, a young girl who delivers a message to Madame Nemirovitch as the train leaves, is caught on board. Throughout the evening, the THRUSH agent and Solo and Illya engage in a battle of wits as the train speeds along its route.

Solo and Illya try to protect Professor Lillian Stemmler from THRUSH after she invents a drug called Plus X, which heightens all the human senses. Unbeknownst to them, she is a THRUSH agent herself who at first cooperates willingly, then has second thoughts. But THRUSH agent Rollo kidnaps her daughter Leslie and forces her to cooperate. The drug is given to three THRUSH agents who will attack a U.S. government plutonium plant using their superior senses, while at the same time the guards will be given a dose of Minus X, which dulls the senses.

A top-level U.N.C.L.E. conference is to be held in Switzerland, but a nearby boys' school is actually a THRUSH front run by Mother Fear and Dennis Jenks that is training its students to be assassins. Solo is captured by the boys, and, when he refuses to reveal the conference location, is forced to operate the controls of two electric trains so they do not collide with each carrying a vial of deadly nerve gas. Illya and Anna Paola, a social worker who resent children, are also captured. The escape, and arrive at the conference just as the boy's choir is ready to kill Waverly and the others with THRUSH rifles from under their robes.

While in Italy investigating a THRUSH plan to divert the Gulf Stream with heavy water, Solo finds himself eluding THRUSH guards, and ends up hiding under the bed of Pia Monteri. Solo escapes a shotgun wedding, the family feels Pia's honor has been compromised, and the girl's American uncles retired Prohibition-era gangsters ""Fingers"" Stilletto, Enzo ""Pretty"" Stilletto, and Federico ""Feet"" Stilletto are called. At the island headquarters of Louis Strago, Illya is tortured by Strago's sadistic female assistant, Miss Diketon. Solo joins forces with the Stilletto brothers to try and rescue him.

THRUSH eastern in Japan acquires a volcano-activating device, and Solo and Illya, along with Cricket Okasada, a film student, infiltrate a toy store and a karate school to find it. THRUSH leader Mr. Kutuzov oversees local THRUSH head Harada in the operation, and Solo finds himself fighting for his life against a life size sword wielding puppet.

In spoof of ""My Fair Lady,"" Solo is recuperating from a fall into a Venice canal, Illya teams with Mark Slate to uncover Baroness Bibi de Chasseur, a THRUSH money courier who has contact with the treasurer of THRUSH. They recruit a barroom entertainer, Rosy Shlagenheimer, an exact double, to impersonate her. The switch is made, but in the confusion the Baroness makes another switch and poses as Rosy, then finds herself falling in love with Slate.

The 'Re-collectors' claim to be trying to locate works of art stolen by the Nazi's but all is not as it appears.

While in Italy investigating a THRUSH plan to divert the Gulf Stream with heavy water, Solo finds himself eluding THRUSH guards, and ends up hiding under the bed of Pia Monteri. Solo escapes a shotgun wedding, the family feels Pia's honor has been compromised, and the girl's American uncles retired Prohibition-era gangsters ""Fingers"" Stilletto, Enzo ""Pretty"" Stilletto, and Federico ""Feet"" Stilletto are called. At the island headquarters of Louis Strago, Illya is tortured by Strago's sadistic female assistant, Miss Diketon. Solo joins forces with the Stilletto brothers to try and rescue him.

Illya Kuryakin infiltrates a South American prison camp where Thrush are storing the 'Ultimate Computer'.

Illya investigates the mysterious disappearance of cats in Soho, and he and Solo discover that a salon run by Madame De Sala is a front for her plan to develop a rejuvenation process, which De Sala plans to use on the now elderly target of her romantic desires, Sir Norman Swickert. Assisted by Joanna Sweet, a nurse, they end up in the bottom of a wine press. Meanwhile, THRUSH agent Jordin plots to obtain the process for THRUSH.

While investigating a THRUSH plot to sabotage space shots, Solo and Illya are incapacitated by a quartzite radiation projector. Waverly assigns new trainee April Dancer along with over the age of retirement agent Mark Slateto find the antidote and destroy the plan. April infiltrates the cosmetics company of THRUSH agent Arthur Caresse as a model, but she is uncovered by Caresse's sister Jean.

Solo and Illya discover that the world diamond market is being affected by a gang of English criminals headed by Blodgett, who smuggle diamonds inside pudding sold unwittingly by Victoria Poque. They enlist the aid of a master diamond thief, Rafael Delgado. Solo and Victoria end up in Brazil, with Solo tied to the front of a cannon and about to be executed.

Alexander (Rip Torn) a megalomaniac industrialist, plans to conquer the world like his namesake, Alexander the Great by breaking each of the ten commandments along the way. he has his henchman Parvix (David Sheiner) steal the army's ""will gas"" to help him do so, and Solo investigates. Solo encounters Tracey Alexander (Dorothy Provine), Alexander's ex-wife, who wants to tag along with Solo to get the money Alexander owes her. The trail leads Solo, Illya, and Tracey to a posh party at Alexander's, where Solo defeats him in a human chess game; to a tomb, where Alexander and his aide Dr. Kavon (David Opatoshu) leave Solo tied under a descending scimitar while Illya and Tracey are hanging over a bottomless pit with a candle burning their rope; To Alexander's farm in Virginia, where Illya is nearly cut in two by various farm implements.

Napoleon Solo is given the job of searching for Thrush security records.

French fanatic Robespierre seeks to destroy France's vineyards in his quest for virtue, and Solo enlists the aid of scientist Raoul Dubois and his daughter Albert in combating the plan. Illya is captured by THRUSH agent Carl Voegler and, with a target painted on his back, is hunted through the woods by Voegler's archers.

THRUSH has developed with the aid of Dr. Elias Swan, a strain of minute, deadly bees. THRUSH agent Mr. Mozart captures Illya and Tavia Sandor and uses a high-frequency sound machine that threatens to shatter their eardrums to force Illya to take him to U.N.C.L.E. headquarters so he can release the bees. Illya does so, but Mozart is intercepted, and in a battle on a rooftop Mozart is shot and the bees get loose.

Solo investigates a girl's school for the daughters of VIP's, including Miki Matsu, who has valuable secret information from her father, a Japanese diplomat. THRUSH agent Jason Sutro has gained the cooperation of the headmistress, Hester Partridge. The assistant dean, Verity Burgoyne, and all of the girl students have been brainwashed by Sutro to go into a trance upon hearing a recording of Brahm's Lullaby, and are ordered to kill Solo.

Alexander (Rip Torn) a megalomaniac industrialist, plans to conquer the world like his namesake, Alexander the Great by breaking each of the ten commandments along the way. he has his henchman Parvix (David Sheiner) steal the army's ""will gas"" to help him do so, and Solo investigates. Solo encounters Tracey Alexander (Dorothy Provine), Alexander's ex-wife, who wants to tag along with Solo to get the money Alexander owes her. The trail leads Solo, Illya, and Tracey to a posh party at Alexander's, where Solo defeats him in a human chess game; to a tomb, where Alexander and his aide Dr. Kavon (David Opatoshu) leave Solo tied under a descending scimitar while Illya and Tracey are hanging over a bottomless pit with a candle burning their rope; To Alexander's farm in Virginia, where Illya is nearly cut in two by various farm implements.

Illya investigates the mysterious disappearance of cats in Soho, and he and Solo discover that a salon run by Madame De Sala is a front for her plan to develop a rejuvenation process, which De Sala plans to use on the now elderly target of her romantic desires, Sir Norman Swickert. Assisted by Joanna Sweet, a nurse, they end up in the bottom of a wine press. Meanwhile, THRUSH agent Jordin plots to obtain the process for THRUSH.