THE MYSTERIOUS MR. M (1946)

The Mysterious Mr. M is a 1946 Universal Pictures movie serial, the 137th and last serial produced by Universal.

Plot
Anthony Waldron intends to steal a new submarine invention from Dr. Kittridge while blaming a fictitious mastermind he calls "Mr. M." To further this plan, Waldron uses a mind control drug he has developed called "Hypnotreme." However, a mystery villain soon appears claiming to be the real Mr. M and starts giving Waldron orders.

Federal agent Grant Farrell, whose brother was killed by Waldron, is dispatched to find the mysterious villain and stop his nefarious plans, teaming up with Kirby Walsh and Shirley Clinton to do so.

Cast
Richard Martin as Detective Lieutenant Kirby Walsh
Pamela Blake as Shirley Clinton, insurance investigator
Dennis Moore as Agent Grant Farrell
Edmund MacDonald as Anthony Waldron, the original villain
Virginia Brissac as Cornelia Waldron
Jack Ingram as William Shrag, the chief henchman
Danny Morton as Derek Lamont, one of Waldron's henchmen
Byron Foulger as Wetherby
Jane Randolph as Marina Lamont, one of Waldron's henchmen
SOURCE:[1]

Chapter titles
When Clocks Chime Death
Danger Downward
Flood of Flames
The Double Trap
Highway Execution
Heavier than Water
Strange Collision
When Friend Kills Friend
Parachute Peril
The Human Time-bomb
The Key to Murder
High-line Smash-up
The Real Mr. M