Following the suicide of a fellow scientist under suspicion of passing information to the Communists, Dirk Bogarde plays an Oxford Scientist who submits himself to a particularly dangerous experiment in total isolation to try and prove that his colleague had been brainwashed. The experiment consists of being submerged in a tank full of water for up to ten hours completely out of touch with the outside world. He is without sight, without taste, without touch, without smell and without hearing, and the result is disturbing to say the least...
