The story opens on the aftermath of an automobile accident, which apparently resulted in a death. The young doctor who looks after the fatality, Dennis Barrows, was involved in the accident, but was not at fault. The police advise him he should have stayed on main roads, but he insists on continuing on. As he makes his way down a dusty road, his car breaks down and he decides to walk to the nearest town. He encounters a barbed wire fence blocking the road with a big sign that says "Private Property – Keep Out". Dr. Barrows crosses it anyway.

He stumbles into a strange town on the coast with a lighthouse. By this time, it is dark and the town seems deserted with only the sound of a barking dog in the distance. Desperate, he awakens the proprietor of the general store, who promptly tells him that they have no phone and no way to help him. After demonstrating to him that he has no choice as he cannot leave, he is let inside.

After introducing himself, a boy who had come in to speak to the proprietor asks him "what's a doctor?" Confused, Dr. Barrows listens to their odd conversation about the boy's ill sister. The boy then offers their spare room to Dr. Barrows for the night, although the proprietor and his mother are both wary of it. Dr. Barrows offers to help the sick girl, but the mother refuses. Suddenly, the lighthouse, seemingly with a mind of its own, starts lighting up the town and focuses on the girl's bedroom. This makes the mother and the boy terribly upset.

The boy, Teddy, asks to talk to Dr. Barrows. He explains that his sister may die, since the light picked her room and begs him to help. Dr. Barrows gives her medicine, but Teddy claims that the beacon might take his sister anyway. Teddy explains that whenever the beacon, which is the light of the lighthouse, picks someone to sacrifice, it takes them. Dr. Barrows begs Teddy to take him to the beacon in order to reason with Seth, the one who runs the lighthouse.

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