Two incidents involving a Peeping Tom are reported from the Swim and Tan Motel to the detective agency belonging to Donald Lam and Bertha Cool. Bertha, meanwhile, has warned Donald to steer clear of the dangerous jobs and stick to aiding solid, sane citizens like Montrose L. Carson. And all Carson wants is the name of the informer in his office who is passing on confidential material to a business rival, Herbert Dowling.

But when Dowling is murdered at the Swim and Tan Motel, it looks as though Bertha has picked the wrong client, and Donald the right girl when he chooses a lively bait to catch the Peeping Tom … and the murderer.