Danny Hayes is an awkward child who is afraid of the dark and the regular target of a local bully named Eric. Eric teases Danny about his interest in Lianna, a pretty student. At home, Danny's mother chastises him for sleeping with the lights on. A mysterious entity comes out from under his bed; he introduces himself as the shadow man, and promises that he will never harm the person under whose bed he lives. The shadow man leaves the house.

The next day, Danny tries to tell his friend Peter about the shadow man, but Peter dismisses it. At school, Danny hears about a series of attacks on children; witnesses describe the attacker as a shadowy man. That night, the shadow man reiterates his promise and then leaves. Danny unsuccessfully tries to take a picture of him. The next day, Danny tries again to tell Peter, but Peter continues to dismiss it. Danny overhears that Lianna needs help in algebra, so he goes to her house to help. She is impressed that he would risk an attack by the shadow man just to help her.

Danny's "bravery" becomes the talk of the school, and he attracts a number of false friends. Peter, believing that Danny's story of the shadow man under his bed might be true, confronts Danny. Danny reacts dismissively toward Peter. Later, Danny challenges Eric to a fight. The shadow man arrives at the appointed time; Eric runs off, but Danny is not afraid of the shadow man. The shadow man begins to choke Danny. Danny is in shock, and demands to know why the shadow man is reneging on his promise of never harming him. The shadow man acknowledges the promise to never harm the person under whose bed he lives, but then states that he is a shadow man from someone else's bed.

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