X... het onbekende

British commandoes on maneuvers near a muddy marsh become ill with mysterious symptoms and horrific burns. Dr. Royston (Dean Jagger), an atomic scientist from a nearby research station suspects lethal radiation but it mystified by the cause. At a nearby hospital, the phenomenon reappears and engulfs more innocent poeople including a hospital orderly whose skin has melted away from his body. Dr. Royston speculates that the unknown force is on a quest to absorb radiation and expands in size and range as it claims more and more victims. As time runs short, he becomes desperate to trap the force before its powers overcome mankind. (officiële tekst van distribiteur)