Professor Brecht, a renowned scientist, is obsessively experimenting in his isolated villa. The object of his studies is "apparent death", with the intention that the human body in a cataleptic state can be cured more easily. He lives with his wife Lisa and several other people: his twin brother Germano; Katia, the waitress; Lailo, his assistant and young student Erina. Having discovered his brother's affair with Lisa, Brecht sets up a plan to kill Germano and take his place. The shock makes Erina dumb. Bercht's persecution of Lisa soon turns the woman mad, while Lailo, wandering in the villa's surroundings, vainly tries to find the key to the mystery. A psychiatrist, Louis, firmly believes Lailo's madness is caused by her inner anguish and seems confident in her recovery. But he's wrong: the demented woman kills Katia and then throws herself out of a window. Brecht takes back his own identity, but his actions will have further tragic consequences...