A woman finds herself unwillingly mixed up in a series of murders. At the behest of the district attorney, private detective Duncan MacLain (Kent Taylor) investigates the probability of corruption in high government circles.

A doctor and nurse solve an operating-room murder.

A detective must solve a case where a girl was murdered in a room--and all the doors and windows were locked from the inside.

Trouble begins when a hated cad of a sponsor is found murdered during the climax of a live radio show. A radio engineer then tries to solve the murder.

Nicholas Rood, dishonest mine owner, finds a Black Doll on his desk and knows that vengeance is about to overtake him for murdering his former partner. He is knifed as he talks to his daughter Marian. She summons her fiancé Nick Halstead, a private detective. He finds that six people had a motive for the murder; Rood's sister Mrs. Laura Leland; her son Rex; Rood's associates Mallison and Walling; Esteban, a servant and Dr. Giddings. Sheriff Renick and his deputy Red get the clues all mixed up, but Nick finally narrows the search down to one suspect...

In this mystery, a newspaper executive and three of his colleagues conspire to have the owner of the highly-respected London Sun committed to an insane asylum. The hapless publisher manages to escape. Soon after, the four collaborators begin dying one-by-one. Oddly their obituaries appear in a rival publication before they are actually killed.

In their third and last teaming, Bill Crane and Doc Williams visit a country estate to investigate threatening letters from the mysterious 'Eye.'