Watch The Avengers

The film begins with Ministry spy, John Steed, in a training field, then shifts to Dr. Emma Peel lounging at home when a phone call orders her to enter a gentlemen's club, where the two first meet. They head for The Ministry to meet the organization's head, "Mother." Mother explains that the weather manipulating Prospero project was disrupted by Emma Peel, a claim that rings false to Mrs. Peel. The pair will work together to discover the true criminal. Mother's number one, Father, claims that Peel suffers from a mental disorder. The duo visits Sir August De Wynter, a Ministry ally.

Steed and Peel head to Wonderland Weather, a business which manipulates weather, finding two dead and dressed as teddy bears. They belong to a secret group, led by De Wynter, and all wear such costumes to conceal identity. Notably, one is a clone of Peel. Steed saves Mrs. Peel right as her double escapes from a roof and vanishes. Steed and Peel revisit De Wynter at home, only to be attacked by robotic bees. They escape with the help of Ministry agent Alice. Peel is captured by De Wynter, eventually smashing through a window, with Steed rescuing her. They retreat to Steed's apartment. Peel winds up being arrested by Father while Steed is away, visiting Ministry man Invisible Jones regarding the map from Wonderland Weather. Steed deduces that Father is plotting with De Wynter. Father and the clone capture Peel, but Mother meets them, soon incapacitated. De Wynter then tells the world leaders that he controls the weather, demanding a high price by midnight.

Father and the clone place Emma in a hot air balloon, where she escapes within a snowstorm. Father and the clone are ended in an explosion. Jones deduces De Wynter's location, sending Steed and Peel there. Emma neutralizes Prospero in time while Steed duels De Wynter. The pair makes it out of the base just before it explodes and share rooftop champagne with Mother.