"The Tomb" tells of Jervas Dudley, a self-confessed day-dreamer. While still a child, he discovers the entrance to a mausoleum, belonging to the family Hyde, whose nearby family mansion had burnt down many years previously. The entrance to the mausoleum is padlocked and slightly ajar. Jervas attempts to break the padlock, but is unable. Dispirited, he takes to sleeping beside the tomb. Eventually, inspired by reading Plutarch's Lives, Dudley decides to patiently wait until it is his time to gain entrance to the tomb.
One night, several years later, Jervas falls asleep once more beside the mausoleum. He awakes suddenly in the late afternoon, and believes that a light has been latterly extinguished from inside the tomb. Taking leave, he returns to his home, where he goes directly to the attic, to a rotten chest, and therein finds the key to the tomb.
Once inside the mausoleum, Jervas discovers an empty coffin with the name of "Jervas" upon the plate. He begins, so he believes, to sleep in the empty coffin each night. He also develops a fear of thunder and fire, and is aware that he is being spied upon by one of his neighbours.
One night, against his better judgement, Jervas sets out for the tomb on an overcast night, a night threatening to storm. As he approaches the tomb, he sees the Hyde mansion restored to its former state; there is a party in progress, which he joins, abandoning his former quietude for blasphemous hedonism.
During the party, lightning strikes the mansion, and it burns. Jervas loses consciousness, having imagined himself being burnt to ashes in the blaze.
He finds himself screaming and struggling, being held by two men with his father in attendance. A small antique box is discovered, having been unearthed by the recent storm. Inside is a porcelain miniature of a man, with the initials "J.H." Jervas fancies its face to be the mirror image of his own.
He begins jabbering that he has been sleeping inside the tomb. His father, saddened by his son's mental instability, tells him that he has been watched for some time and has never gone inside the tomb, and indeed, the padlock is rusted with age. Jervas is removed to an asylum, presumed mad.
He then asks his servant Hiram, who has remained faithful to him despite his current state, to explore the tomb – a request which Hiram fulfills. After breaking the padlock and descending with a lantern into the murky depths, Hiram returns to his master and informs him that there is, indeed, a coffin with a plate which reads "Jervas" on it. Jervas then states that he has been promised burial in that coffin when he dies.
- Several comic book versions exist, including The Worlds of H.P. Lovecraft: The Tomb (1992, 1997).
- A 2007 film was released to DVD with no ties whatsoever to the short story, despite being promoted as HP Lovecraft's The Tomb. The movie's plot was similar to the Saw series of horror films.
- The band The Darkest of the Hillside Thickets take their name from a phrase in this story.
- The podcast Stuff You Should Know presented a reading of "The Tomb" for their Halloween podcast in 2010.
- The Order of the Solar Temple's 2014 self-titled album includes a track titled "Jervas Dudley",