Wilde's story is narrated by a friend of a man called Erskine, who is preoccupied by the Hughes theory. Erskine had learned the idea from one Cyril Graham, who had tried to persuade Erskine of it based on text of sonnets, but Erskine was frustrated by the lack of external historical evidence for Willie Hughes's existence. Graham tried to find such evidence but failed; instead, he fakes a portrait of Hughes in which Hughes is depicted with his hand on a book on which can be seen the dedication from the sonnets. Erskine is convinced by this evidence, but then discovers the portrait to be a fake, a discovery that leads him to yet again doubt the existence of Willie Hughes. Graham still believes in the theory, and to prove it, shoots himself.
Erskine recounts these events to the narrator, who is so struck by the Willie Hughes theory that he begins his own research and further fleshes out Graham's findings until he is without a doubt that Willie Hughes was real and was the subject of the sonnets. He presents the evidence to Erskine but then finds himself strangely divested from it and loses faith in its basis in reality.
Erskine's belief, however, is renewed; he sets off at once to try to find a trace of Willie Hughes. But like Graham, he finds nothing. The narrator maintains that there was nothing to be found - that Hughes never existed. Erskine sends him a letter, in which he tells him that the truth is in front of him and, as a sign of complete faith in it, is now twice stained with blood. His friend goes to his hotel in Cannes and finds Erskine dead.
He assumes Erskine committed suicide like Graham, but the doctor tells him the real cause was a lingering illness that Erskine had known about for some months; he had come to Cannes specifically to die. He left his friend the portrait of Mr. W. H. The portrait now hangs in his home, where many comment on it, but he does not tell of its history. He sometimes wonders to himself, however, if it might be true after all.