English secret armaments programming is confronted with Communist infiltration as a Leeds plant, along with M. I. 6, goes on the hunt for the men involved in the theft of photographs of a new torpedo. Ewart hares off after Miranda, whose husband's weaknesses have turned him Red, and after the personnel manager; both traitors renege and Ewart's new job is to invent a counter-move to the torpedo in the event the plans were received and interpreted. Characters built for chain reactions. Able.