Mandrake the Magician (1939) is the seventh serial released by Columbia Pictures. It was based upon the King Features comic strip of the same name.

Plot
Mandrake and his assistant Lothar are working the cruise lines and make the acquaintance of Professor Houston who has developed a radium energy machine, which is much coveted by a masked crime lord known as “The Wasp”. The Wasp unleashes his army of accomplices in waves to steal the invention by any means necessary. Mandrake and his allies finally catch up to “The Wasp” and discover the crime lord is actually a scientist who posed as a close friend of Houston’s.

Chapter titles
1. Shadow on the Wall
2. Trap of the Wasp
3. City of Terror
4. The Secret Passage
5. The Devil’s Playmate
6. The Fatal Crash
7. Gamble for Life
8. Across the Deadline
9. Terror Rides the Rails
10. The Unseen Monster
11. At the Stroke of Eight
12. The Reward of Treachery

Cast
Warren Hull as Mandrake the Magician
Doris Weston as Betty Houston
Al Kikume as Lothar, Mandrake’s Assistant
Rex Downing as Tommy Houston
Edward Earle as Dr. Andre Bennett/the Wasp
Forbes Murray as Professor Houston
Kenneth MacDonald as James Webster
Don Beddoe as Frank Raymond
Dick Curtis as Dorgan, a henchman
John Tyrrell as Dirk, the “spearpoint heavy” (chief henchman)
Lester Dorr as Gray