Sir Richard, the new Squire of Castringham, rides to his residence. Mrs Chiddock, the housekeeper, shows him a portrait of his great uncle Sir Matthew, who Sir Richard strongly resembles. The line of succession has been blunted, but Sir Richard hopes to change that with his wife-to-be, Lady Augusta.

Sir Richard plans a new family pew to the church, but a grave will have to be moved first. It belongs to Anne Mothersole, who was hanged for witchcraft. Farmers pleaded with Sir Matthew for clemency in her case, but he refused to change his evidence against her. While speaking with Dr Croome, Sir Richard unknowingly speaks about her with the same words used by his relative decades earlier.

Lady Augusta comes to see Sir Richard before setting off to Paris to get her trousseaux. As she leaves, Sir Richard stands by the large ash tree next to the hall and is disturbed by faint sounds of crying.

The past: Sir Matthew speaks with Anne while she picks plants and herbs from the riverbank. That night, Sir Matthew sees Anne cutting sprigs from his ash tree and pursues her, convinced that she has changed into a hare. When he reaches her house, she seems to have just awoken, to his consternation.

Sir Richard has visions of Anne tortured for witchcraft as witnessed by Sir Matthew. Sir Richard decides to move into the room originally slept in by Sir Matthew. Anne's grave is opened and found empty. Dr Croome tells Sir Richard that Sir Matthew, troubled by the execution of Anne, sought refuge in 'sortilege', picking phrases at random from the bible. The night before Sir Matthew's death, Dr Croome saw a strange creature running up the ash tree. Sir Richard decides to cut down the tree.

That night, Sir Richard opens the bible at random and reads the words, 'Thou shalt seek me in the morning, and I shall not be'. Giant spiders with grey fur, expressive eyes and mouths making mewing noises invade his room and cover his body, killing him. Anne Mothersole's final words, 'Mine shall inherit' are heard. Mrs Chiddock enters and, seeing the creatures return to the tree, throws her oil lamp at them. The creatures burn as the tree is consumed in flames. The next morning, the skeletal remain of a woman in a crouching position are found inside the trunk of the tree.