When two scientists at a top-secret government installation devoted to space research are killed -- in their own test chamber, seemingly by an experiment gone awry -- Dr. David Sheppard (Richard Egan) is sent out from Washington to investigate. Sheppard mixes easily enough with the somewhat eccentric team of scientists, though he always seems in danger of being distracted by the presence of Joanne Merritt (Constance Dowling), who serves as the aide to the project director Dr. Van Ness (Herbert Marshall) but is, in reality, another security agent. Sheppard is as puzzled as anyone else by the seemingly inexplicable series of events overtaking the installation -- properly operating equipment suddenly undergoing lethal malfunctions, and the radar tracking aircraft that aren't there -- until he puts it together with the operations of NOVAC (Nuclear Operated Variable Automatic Computer), the central brain of the complex. But the mystery deepens when he discovers that NOVAC was shut down during one of the "accidents" -- and even the computer's operators can't account fully for the whereabouts of GOG and MAGOG, the two robots under the computer's control.