An underrated sci-fi thriller, based on the novel by Frank M Robinson. Set in a research institute, the plot concerns the hunt for a mysterious, murderous super-brain who is evidently one of the scientists. The investigation, led by Hamilton, whose mind becomes increasingly tampered with by his quarry's power, takes him through a cross-section of contemporary America in search of the killer's past. More than once the film seemingly goes off at a tangent, only to return chillingly to the matter at hand: as when a woman kisses one of the researchers during a party into which the film has become sidetracked, only to discover that he's dead. George Pal's special effects are excellent, and Hamilton's performance is surprisingly good.