Detective Weekly #379

This issue of Detective Weekly contains two serials featuring espionage and criminal intrigue. The lead story follows detective Blake investigating a series of murders at an English inn, where victims speak of a mysterious "monster." Blake discovers a Nazi submarine hidden in an underground cavern system beneath the house, connected to the murders. The climax involves Blake pursuing German operatives through flooded tunnels to reach the secret submarine dock, where he confronts the murderer and German naval personnel.

The second serial, "Gerald Vermer's" story (continued), introduces the mysterious villain XI—a Nazi agent orchestrating a coordinated sabotage campaign across Britain using domestic extremists as unwitting operatives. XI reveals plans to strike simultaneously in factories, food storage facilities, and railway stations. Secret Service agents Michael Dene, Reverend Colgate-Jones, Carol Wray, and others are captured and interrogated by XI, who discloses the signal will be given Tuesday the seventeenth instead of the twenty-first. The issue also includes a "Police and Detective News" summary section.