A pair of agents from the Office of Scientific Investigation, Dr. Jeffrey Stewart and Dr. Dan Forbes, are sent to investigate a local appliance store. All of the store's clocks have stopped at the same time, while metal items in the store have become magnetized. A source for this is traced to an office located directly above the store, where various scientific equipment is found, along with a dead body. There are also signs of radioactivity, but the exact cause of the store's anomalies is clearly no longer in the room or even in the immediate area. Investigation and a request for citizen input eventually leads to an airline flight carrying a scientist, Dr. Howard Denker, who has developed signs of radiation sickness related to something he is carrying in a heavy briefcase and which he clutches irrationally. Before dying, he confesses to experimenting with an artificial radioactive isotope, serranium, which he had bombarded with alpha particles for 200 hours. Unfortunately, his so-far microscopic creation has taken on a life of its own: the new isotope must absorb energy from its surroundings every 11 hours; in the process it doubles its size and mass each time, releasing deadly radiation and incredibly intense magnetic energy. The OSI officials determine that, with its rate of growth, it will only be a matter of weeks before the isotope becomes heavy enough to affect the Earth's rotation on its axis, eventually causing it to break out of orbit. They also discover that the isotope is impervious to any known means of destruction or rendering it inert. The only answer appears to be using a Canadian experimental power generator, dubbed the Deltatron, being constructed in a cavern under the ocean. The hope is that they can bombard the isotope with so much energy in one surge that it will neutralize itself with its own "gluttony". The two governments agree on this proposal, and the isotope is transported to the Deltatron project site, but there is a last minute objection from the engineer in charge. With no time left, the lead OSI agent, Dr. Jeffrey Stewart, commandeers the huge device, a cavern-filling, multi-story machine. He risks his life by activating it and revving it up to maximum output, barely escaping just before sealing off the cavern. The machine powers up and the isotope is successfully pushed beyond its limits, completely destroying it, although the Deltatron has also been destroyed in the process. All trace magnetism which it had produced after every energy absorption has now disappeared. The Earth has been saved from destruction by the efforts of the Office of Scientific Investigation. Life returns to normal, as shown by lead OSI agent, Dr. Jeffrey Stewart and his pregnant wife Connie completing the purchase of their first house and moving in shortly thereafter.
For the Deltatron, the film used ten minutes of footage of the atom smasher from the German science fiction thriller Gold, directed by Karl Hartl and produced by UFA. Although the music was composed by Blaine Sanford, according to IMDB, it was in fact performed by Paul Beaver. The Los AlamosMANIAC computer was featured in an effort to lend a scientific air to the film. The UCLAdifferential analyzer from the same era is also shown briefly for the same reason.
