The Electronic Monster (1958)

Jeff Keenan, insurance investigator, checks out the car-crash death of film star Clark Denver in the south of France. He learns that Denver, and two other victims of recent suspicious deaths, all knew the lovely Verna Berteaux...and all had been patients at a private psychiatric clinic, being treated by electronically induced dream therapy. But the deaths are only a byproduct of a sinister plot; and Zakon, owner of the clinic, is due to marry Jeff's old flame Ruth...