Top secret information is leaking into Europe from a funfair somewhere in Southend. In an attempt to solve the mystery, Steed (Patrick Macnee) takes a job at the funfair, but is found out. Steed is imprisoned on the ghost train, where he finds a machine that is transmitting coded information to Europe.

One-Ten believes a man murdered live on TV has been killed by the assassin, 'The Teddy bear'. Steed is turned into bait to trap the killer.

Steed and Cathy must battle a host of foreign agents in order to reclaim a missing flask of secret new rocket fuel while in Marseille.

Steed is sent to help in the Balkans when a President is intimidated by a masked assassin and his bodyguards are murdered one by one.

The Avengers are called upon when the Home Office becomes concerned with the increase of gunrunning in Africa and stockholders of a British gun manufacturer start getting killed.

A microfilm of North American early warning plans has been stolen and a fading film star may be involved. Steed and King are assigned to the mission.