After forty years of good and faithful services, Robert T. Ironside, reprocessed police force of San Francisco, is finally on the point of tasting with the joys of a rest deserved well with Katherine, his wife, in their vineyard recently bought.
However, a few days after his official departure, he is contacted by persons in charge for the police force of Denver, which offers the post of general manager temporarily to him their services, following the assassination for preceding occupying of the station in question. Initially reticent, Ironside ends up yielding and, with the agreement of his wife, agrees to take up the challenge, the more so as he has pleasure to find Susan, the girl of the one of her former assistants. He realizes quickly that the young woman seems tormented by preoccupations with a personal order. Indeed, she has discovered that its been engaged Mike, also has just organized, the horn for some time with Judy, another woman police officer. In spite of the vehement denials of the young man, she decides, one night, to follow him to the residence of his mistress and surprises them in obvious offence. Upset, she flees precipitately. The following day, the police force discovers the bodies of Mike and Judy, assassinated using a weapon of police force. The conclusions of the investigation are not made wait, and Susan, whose alibi remains at the very least smoky, is shown at once of murder…