A young boy named Palmer lives in a town called Waymer, which celebrates an annual Pigeon Day. Pigeon Day involves trapping pigeons in crates and releasing them to be shot in the air. When the book opens, the town's 63rd annual Pigeon Day is intended to raise money for the city's playground. Ten-year-old boys in Waymer can accept the honor of picking up the wounded birds that have not yet died from a gunshot wound and wring their necks to "put them out of their misery."
When Palmer turns nine, his peers pressure him to join them in anticipation of becoming the best "wringers," boys who wring the necks of pigeons. Palmer's mother does not approve of his friends for this reason, but she cannot force Palmer to find other friends. Palmer finds himself anxious to live up to his father's example, as he was known as one of the best wringers when he was Palmer's age. Though Palmer is actually reluctant to participate in the Pigeon Day wringing, he does not express this out of fear of being ostracized.
When a pigeon comes to Palmer's window, he secretly takes the bird in as a pet and names it Nipper. To Palmer's surprise, his parents both learn of the existence of the pigeon but respect his wishes to keep Nipper a secret. Keeping Nipper also allows Palmer to befriend Dorothy, a girl who opposes the pigeon shooting festival because of its cruelty toward the birds. When the day of the shooting comes, Palmer is anxious because he has allowed Dorothy to release Nipper in hopes that the pigeon will avoid capture.
Dorothy reveals that she released Nipper near the railroad tracks, unaware that people capture the pigeons at that exact location to crate them for the shooting. When the pigeons are released, Nipper is wounded. One of Palmer's friends, Beans, happens to be at the shooting, and he brings the pigeon back onto the field to be killed by the sharpshooter. Palmer chooses to carry Nipper off the field in the midst of the gunfire. As Palmer walks through the booing crowd carrying Nipper, he sees a kid nearby reach out to stroke Nipper's wing. The kid asks his father if he can have a pigeon of his own.