When Steed takes prime witness Miranda Loxton to a safe house to protect her from Murder-International hitmen, Tara is kidnapped. She escapes to find herself in her worst nightmare. A booby-trap in Steed's apartment kills Mother and Tara may be the only one with the hidden knowledge of where Steed has gone.
Whilst on a top secret security assignment, Tara comes under suspicion of being a double-agent. She must cast similar suspicion on Steed if she is to prove that she has been framed. An enemy agent, Gregor Zaroff, hopes to put the Government's new anti-missile defence system, code named 'Field Marshall', out of action by convincing Steed and Mother that Tara has betrayed the system's secrets. (Source: en.wikipedia.de)
When an agent at the Ministry of Top-Secret Information is murdered, Steed and Tara have little difficulty in locating the man responsible. But when a handwriting test indicates that he is Boris Kartovski, someone Steed thought he had killed in Berlin 5 years before, our heroes find themselves drawn into the dangerous experiments of Dr. Constantine.
Problems of a secret leakage from Cypher HQ and the disappearance of agent Jarret are first handed to rival Department MII2, and then to Mother's group. But why does everybody at Cypher HQ claim never to have seen Jarret and state that the only thing worthy of note that happened yesterday was that it rained?
Steed's colleague Sean Mortimer comes to see him in a very confused state. He knows there is a traitor in the organization but he has been drugged to put him in an amnesiac state and he can remember little else. Mrs. Peel investigates but she too falls prey to the drug as she and Sean are abducted by bikers. It is down to trainee agent 69, Tara King, to whom Steed is introduced by spymaster 'Mother' to help him save the day.