A traitorous actress is pressured by threats into enticing her terrorist lover to leave the safety of neutral Switzerland and join her in France, an ally of England.

A quiet Englishman, Caypor, has chosen to spend the war in Switzerland, as his wife is German. But Ashenden suspects he may be a spy, and may have to be killed.

Ashenden is sent to revolutionary Russia with funds for delivery to Kerensky, the Prime Minister of the Russian Provisional Government, who England supports.

Ashenden is joined by an eccentric assassin known as "the hairless Mexican" who is dangerous.