Steed's department is guarding M. Roland, A UN negotiator in London for important talks, but cannot prevent an assassination attempt. Indeed, it seems that one of Steed's colleagues is selling secrets - and Steed finds that even he is under suspicion.

Venus has her camera and films stolen whilst taking pictures in a fun fair. One film is missed, however, and when developed a face can be seen in the Hall of Mirrors - that of Trevelyan, the cypher clerk who has committed suicide. But Venus's photograph was taken after the man's death.