The members of a society that watches Venus are dying one by one from something that turns them completely white, so Steed joins them to flush out the culprit while Peel chases a light that seems related to the killings.
The executives of several ceramics companies are being driven crazy or killed by fear. The trail leads to a consulting company with some unusual techniques for helping their clients beat their competition.
Two spies have obtained information about a secret missile base which they are passing to the other side, via a person known as Captain Caruso, whom the Avengers are charged to locate. In the event the good Captain turns out to be a trained parrot who possesses a photographic memory . . .
Several businessmen have been killed, the murderer having apparently clawed them to death so that the initial suspect is an author who owns a bird of prey and had a grudge against a victim who ran a publishing house. However, the discovery of a comic called 'The Winged Avenger' featuring a super-hero is found by the latest victim. And could the invention of Professor Poole, boots that allow the wearer to climb walls and scale ceilings, be involved?
Five years after a mine disaster, Mrs. Peel and Steed are called upon to investigate the spooky goings-on at the local inn. The ghost of the 16th Duke of Benedict, who was reputedly lost in the mine disaster, has been seen wandering the area and Emma joins SMOG and FOG in a ghost hunt. The Duke's ghost supposedly takes Emma with him to his final resting place in the collapsed mine, but Steed descends into the shaft to rescue her. He finds a secret underground city that is being used to stage an invasion of England; the mine disaster was just a cover-up for the plan. ...
Somebody is systematically killing off foreign agents and Steed, who is initially implicated, declares a truce and calls on his Russian opposite number, Nutski. Along with Soviet agents Anna and Ivan the Avengers discover SNOB, an exceedingly English gentlemen's club with murderously patriotic members.
The Avengers "are needed" after reports that a motorist has repeatedly run over and supposedly killed the same person. Their investigations lead them to the country and the top secret Neoteric Research Unit, which is run by the appropriately-named Dr. Frank N. Stone, who has made a startlingly life-like robot of himself, so much so that Steed finds it hard to tell the two Stones apart.
Z.Z. von Schnerk, a mad Teutonic film director of the Erich von Stroheim variety, along with his has-been leading actor and actress, Stewart Kirby and Damita Syn, capture Mrs. Peel in an effort to make a movie about her life and exciting adventures. Unfortunately it is to end with her violent death so Steed has to follow the clues to find her.
Steed is invited to a party on an aeroplane with six other people who include a matador, a cowboy and a circus strong man. As the pilotless , remote-controlled craft takes off, a voice announces that they are bound for a desert island where one of them will be revealed as a super-killer. Mrs. Peel has to work out how to get to her partner as the bodies start to pile up.
Whilst travelling on an express train on a quest to find a missing agent, Steed and Mrs. Peel get caught up in an assassination attempt on the life of the British Prime Minister on the part of a disgruntled and murderous ticket collector. They are helped in their efforts to foil him by Mr. Crewe, an eccentric owner of an abandoned station.
Mrs. Peel is invited to a bridge party at a house on Exmoor but when she arrives she discovers that she has been lured there by a man known as 'The joker'. She had once helped to put him in prison, but he has now escaped and with his two crazy accomplices, subjects Mrs. Peel to a series of lethal tricks and traps as Steed arrives to help her.
Mad scientist Dr. Krelmar is working on a machine that allows two people to swap minds and enemy agents Basil and Lola intend to use it with the Avengers to get them to destroy their network. Basil exchanges personalities with Steed but Mrs. Peel is suspicious that the man who looks like her partner is acting out of character and has to persuade the real Steed what is going on.