One day when Pelayo, a coastal villager, goes to dispose of crabs that have washed ashore onto his property, he discovers an old man with wings lying face down in the mud. The toothless creature is bald and dressed in rags. As Pelayo and his wife, Elisenda, carefully examine the creature, looking for clues to its origin, it responds to their questions in a tongue that they cannot identify. They suspect that he is a castaway from a ship. Other villagers who see the old man offer theories about his origins and appearance. The couple plan to set him adrift on a raft, but they first imprison him in a chicken coop. When a large crowd gathers around the coop, Pelayo and his wife decide to charge admission to view him, thereby creating a circuslike atmosphere.
The local priest, Father Gonzaga, is disturbed by rumors that the mysterious winged creature might be an angel, so he comes the next day to investigate. When the old man fails to understand Latin, the priest denounces him as an impostor. Nevertheless, curious people travel great distances to see the creature, and a carnival arrives to take advantage of the large crowds. Father Gonzaga, in the meantime, writes to the pope in an attempt to ascertain the church’s official position on the creature and the apparently “miraculous” occurrences that the crowds associate with the old man. The Vatican demands to know if the old man knows Aramaic, if he can fit on the head of a pin, and if he has a navel. Meanwhile, the sick and the handicapped come to the old man in search of cures. The old man does seem to perform miracles, but these miracles are gratuitous in that they are unrelated to the sickness involved. A blind man, for example, grows three new teeth.
The crowds begin diminishing after the carnival puts on display a woman who was transformed into an enormous spider for having attended a dance without her parents’ permission. Nevertheless, Pelayo and his wife have profited so greatly from their enterprise that they purchase a new house and fine clothing. After their chicken coop collapses, the old man moves into the couple’s home, where he becomes a nuisance. Over the years the old man makes feeble attempts to fly, but not until the end of the story does he finally gain sufficient strength and altitude to fly away.