Ear, nose and throat specialists are sneezing themselves to death, each after receiving a mysterious empty envelope. When Tara is kidnapped, Steed takes great care over his morning mail.

Trusted agent Melville has lost three partners in quick succession, and seems to be lying at every opportunity. Is he really the man to partner Steed in an attempt to convict Lord Edgefield, noted blackmailer? And what is the odd connection between this whole affair and daily milk deliveries?

Security lapses seem to point to top civil servants suddenly falling in love and giving secrets to an enemy agent disguised as a char lady. Steed investigates, but first has to save Tara from killing herself out of unrequited love.

When a member of the International Disarmament Committee is stabbed with a swordstick on a foggy night, it looks like the Gaslight Ghoul, murderer of the 1890's, has set up in business again. Can Steed and Tara catch him before the committee is severely lacking in personnel?

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)