The Editor of the Daily Clarion newspaper hires writer and amateur criminologist Steve Colt to solve a series of murders, all involving venomous spider bites, with the aid of his best reporter Joyce Chambers.

Meanwhile, the evil King Hitomu has sent his daughter Sombra to the United States to fulfill his plan for global domination by stealing a prototype "Atomic Rocket Engine".

Posing as a fortune teller, and assisted by her two loyal henchmen, Sombra sets about stealing the prototype and its secrets by utilizing her cunning nature, array of lethal gadgets, and ability to impersonate any woman she chooses with the aid of masks and wigs.

[1] In the early 1950s, The Black Widow was one of fourteen Republic serials edited into a television series.

[1] The Black Widow was one of twenty-six Republic serials re-released as a film on television in 1966.