Highly radioactive material is transported to a nuclear plant. One of the workers, Harry Welles, has an accident with one of the drums and gets in touch with some dust which he thinks is deadly and contagious. He runs away in panic and locks himself into his room. Later his fiancee knocks and worries about him. He is so afraid that anything might happen to her that he sacrifices the engagement, fearing she might stay with him and gets infected too, if he told her the truth.
He goes on running away, a hunted man. On his run through gardens he becomes hungry and thirsty and steals oranges. A girl who watches him shows him his doll. In fear he might contaminate the girl, he hits the doll. The doll’s head goes off and this frightens the girl. She calls her father.
By mistake the father shoots at Mathews, a police officer, who’s been after Harry to inform him that he is not contagious and that he will recover. Mathews can put things straight there, but Harry does not listen. He pretends to come along with the officer, but uses the chance to be close to him to get his gun. Mathews later on can convince him that he won’t die and that he is not contagious.