Starting with a vieew of various exhibits from the Black Museum, news of a possible new entry arrives. A fire is just smoldering out when the Scotland Yard inspectors arrive. Could it have been suicide? Maybe, but not with a bullet hole in the victim’s back.
The victim is found to be Duncan Frazier, a Marine who has been missing from his unit. Or could it be a switch, and a partner in crime named Patterson is dead? Based on dental records the body is confirmed. Troubles in working with local police, and contradicctions in witnesses who knew either Duncan, or Pattersson are portrayed.
The search for Patterson is made all the more dirfficult, since he is average in description, with no distinguishing marks. A thin trail is observed, and a watchful eye is kept. A carefully planned trap is layed, but will the crook walk into it?