 Lab worker Harry Wells is accidentally exposed to radioactive material. He erroneously believes that the contact will prove fatal and he begins acting irrationally. He deserts his girlfriend Fay and flees toward a remote and wooded area where he believes he will pose no danger to anyone else. Dan Mathews, Sergeant Moore, and a radiation expert named Garson pursue Wells in the rough terrain to try and bring him back for emergency decontamination. They learn his approximate whereabouts after he injures a little girl while attempting to avoid touching her. Dan finds Wells and initially wins his confidence by using guile and psychology. However, he is forced to resort to harsher measures when Wells panics again.