When the draconian Hays Code began to be seriously enforced in 1934, horror films predictably suffered a decline. Thus, Boris Karloff returned to his native England to make two horror films which weren’t constrained by Puritanical censorship. One of those films was The Man Who Changed His Mind (also known as The Man Who Lived Again and The Brainsnatcher), which released 11 September 1936 in London.
Dr. Laurience (pronounced Lorenz) (Karloff) was once a respected, venerable scientist, but now he’s fallen from grace and is forced to live off of philanthropist Lord Haselwood’s charity if he wants to continue conducting his experiments. The only people in his corner are wheelchair-bound Clayton (Donald Calthrop) and young surgeon Dr. Clare Wyatt (Anna Lee, wife of director Robert Stevenson).
Laurience feels close to a breakthrough with his dream project of transferring brains into other bodies. The animal or person’s thoughts and personality will remain the same, but they’ll reside in a different body. To prove his theory, Laurience conducts the experiment with chimpanzees.
Convinced of his success, Laurience presents his findings at a scientific meeting. But instead of believing and embracing him, everyone in attendance laughs at him and leaves. Not one person takes him seriously, no matter how much he cajoles, pleads, and finally threatens them.
Back at the lab, Lord Haselwood tells Laurience enough is enough, and that he’s cutting off his financial support and use of the facilities. Laurience tries once more to prove his research is on the level, and when Haselwood remains stubborn, Laurience takes matters into his own hands.
The first brain-body switch with humans is a most smashing success, and Clayton acquires Haselwood’s body. He’s particularly delighted to finally be able to walk again, and refuses to give his new possession back. This loan soon becomes permanent by default, thus granting Laurience unlimited access to the supposed Haselwood’s wealth and patronage.
The plot thickens when Clayton discovers, to his great horror, that his new body isn’t as perfect as he assumed. Though Haselwood can walk, he also has a weak heart which requires medication. In desperation, Clayton begs Laurience to do another switch and give him a better body.
Haselwood’s son Dick, who’s courting Clare, is also unnerved when he visits to ask for a blessing on his hoped-for marriage and finds a father radically different from the one he’s known all his life.
Laurience not only refuses Clayton’s request, he also begins plotting to switch his own body and brain with Dick’s. Clare begs him to reconsider these mad experiments, but he’s bound and determined to continue down this path to power, money, and glory.
Potentially disastrous consequences may await if this plan goes ahead.