Following the vicious murder of a young girl, suspicion falls on a half witted youth living in his aunt's boarding house. After a second murder Inspector Allen exposes the real killer.

A blackmailer is found dead in a locked room and all the suspects have unbreakable alibis.

A valuable diamond is purchased by a man-about-town who then disappears and his cheque bounces. His solicitor hires a private investigator who seeks to track down the man and his female companion but the fugitive turns up dead.

When a convict escapes from prison, to be re-united with his girlfriend and his stolen £20,000 he left with her for safe keeping, he is in for a series of surprises and then a trip to the seaside and a police chase follows.

When Audrey leaves prison after being framed for jewel theft, she asks stepsister Dora for shelter. Dora takes Audrey to a party hosted hosted by Lacey, her boyfriend. Lacey complains about his neighbor, the mysterious Mr. Malpas, who makes strange noises all night and is never seen. Next day, Audrey gets a job offer from Malpas, triggering a plot involving a missing heir, diamonds and kidnapping.

After a visit from a mysterious stranger from his past, enigmatic millionaire John Trasmore is found dead - shot at close range locked in his own strongroom, with the only key on a table in the middle of the room.

A company-owner arrives home from a night out with his wife, disturbs a burglar, and is shot. A detective starts investigating the case, to find out who is responsible.