Book #17 in his own series and #23 in the series.
Marshall of the Special Branch entices both Papa Pontivy and Bernard Newman into helping in an espionage-hunting case. Usually the Soviet operatives are very sophisticated and hard to spot. Not so with newly arrived Tomski who seems to make it a point to stand out as a spy. The question then is why. The answer will lead them all into a matter involving blackmail, theft, and murder.