Inman sends Jordan to investigate the leader of a pro- germ-warfare group.

Starring Derren Nesbitt, Fulton McKay and Morris Perry. In the last of the present series, Britain's top code and cypher-breaker is an expert chess player. When he has to mingle with Communist players in a tournament, Inman goes along to keep an eye on him. Moxon, meanwhile, is playing a far more dangerous game. The pawns being Jordan and a former girl friend.