The Magnetic Monster.

Office of Scientific Investigation (OSI) agents are sent to investigate a local appliance store. The store's clocks have stopped at the same time, while metal items in the store have become magnetized. Investigation and a request for citizen input eventually leads to an airline flight carrying a scientist, Dr. Howard Denker (Leonard Mudie), 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