Ray Browne

Steed sends Cathy to visit Plato – the world’s most advanced computer - and they discover that the machine can remember a murderer.

The Nutshell is the name of a secure underground bunker, to be used by the government in the event of a nuclear war and Steed and Mrs. Gale are shown around it. When military secrets start to be leaked the finger of suspicion points to Steed as a traitor and it is down to Mrs. Gale to clear her colleague's name.

Steed attends the funeral of his former batman Wrightson, who had become a draughtsman on a modest salary in civilian life. However, at the will reading everyone is shocked to learn that he was exceedingly rich and apparently by honest means. Steed and Mrs. Gale investigate and uncover an ambitious plot involving insider trading.