In Charles Butler’s Calypso Dreaming Tansy’s experiments in magic have made her more aware of and sensitive to the supernatural; she sees Calypso in the back of Dominic’s van when her mother does not. Calypso is a selkie, a seal child, and she has the power of making her dreams come true. Tansy sees her astral body in Dominic’s van, rather than the four year old herself, as Calypso is sleeping up at the Manor house, where she and her mother, Dominic’s sister, live. Dominic has powers of his own, however; he is a member of the order of Asklepius and has the gift of healing. But even Dominic’s power is insufficient against Calypso’s, whose dreams have become possessed by a spirit that inhabits the island of Sweetholm. He wakes up and finds himself on the edge of a transformation – there are wisps of feathers growing from each of his knuckles, his fingernails have become claws and his hearing has sharpened. He realises that everyone is in danger and tries to asphyxiate Calypso with a pillow in order to stop her dreams. However, his sister Sophie, catches him in the act and attacks him with a log from the fireplace. She screams “Anathema. Anathema maranatha” at Dominic, cursing him and he flees from Sophie and the Manor, and as he flees he transforms fully into a heron which, as it flies away, is then mobbed and killed by seagulls.
Tansy’s father Geoff is luckier than Dominic. Davy Jones, Sweetholm’s general handyman, is obsessed with St Brigan and he creates a shrine to her and an idol of her in a cave under the Tor on Sweetholm. He intends to sacrifice Geoff Robinson to St Brigan as he has already sacrificed Geoff’s brother John, in whose home Tansy and her parents have been staying on Sweetholm. Geoff manages to escape his intended fate, mostly due to Davy Jones killing himself instead, but he is trapped in the cave under the Tor and that is flooding. To make matters worse, Tansy’s mother believes Davy Jones’ story that Geoff has gone back to the mainland and his mistress, but Tansy does not. She and her friend Harper, a boy about her own age, set off for the Tor to see if they can find her father. Fortunately they discover Geoff, but are nearly killed in the cave when it floods. They are rescued, after a fashion, by Calypso’s seal father, who destroys the idol, releasing the spirit that had been controlling Calypso’s dreams. Tansy and Geoff return to the mainland, leaving Tansy’s mother on Sweetholm. Calypso and Sophie also leave under a cloud of suspicion as Calypso is believed, by the islanders, to be a witch.