Millionaire Walter Craig disappears from his home, and special investigator Nick Trayne is called upon to solve the mystery. Nick and his secretary Betty Hilton discover Craig in the library of his home a couple of nights later…minus his mental faculties. Dr. Taggart and Dr. Bruhning opine that while half of Craig’s brain is missing, he will definitely live on indefinitely. Tony Weldon, friend of the family lives on Craig’s estate in a small cottage away from the big house, and assists in caring for Craig. George Phillips, another friend of the family, is killed and Nick discovers the body with Craig standing over it. Nick and Betty do some fast sleuthing and find that a man named Carson has purchased the chemicals and rented a house in which Craig was subjected to the treatment that destroyed part of his brain. The real estate agent, however, knows the man to whom he rented the house only by his voice, so Nick summons all the relatives and freeloaders and household help in order that he can make recordings of their voices. That night, one of the suspects attempts to kill Nick, but Nick overpowers him and it is revealed that the culprit is…
http://www.imdb.com/title/tt0034985/

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