Original publication: 1964, Atlantic-Little, Brown
Original cover and illustrations:​ Beth and Joe Krush
Working titles:​ The Other Unicorn; Cory Bewitched; A Spell Has Been Cast
Awards / Recognition: Silver Medal, 1964 Commonwealth Awards; Runner-up, Edgar Award; The Horn Book Fanfare Best Books of 1964

From the flap:

"Tarnhelm. The very name of the great old house on the cliffs beside the Pacific Ocean spells hope and mystery. Here, with Uncle Dirk and his mother, Cory Winderslow will surely find a home. But whens he arrives from the East there is no one to meet her at the airport. The strange old woman who offers her a ride to Tarnhelm is prying, and the things she says about Uncle Dirk are disturbing. It is Peter, a resourceful neighbor boy, who leads Cory over treacherous cliffs to the door of Tarnhelm, and the Scottish caretakers, Fergie and Andrew, make her welcome.

Uncle Dirk had written wonderful letters, and he had invited her to stay at Tarnhelm. The little silver unicorn Cory wear around her neck is similar to the unicorns Uncle Dirk has carved. When Cory learns the truth about her Uncle and grandmother, she feels her entire world crumbling about her. 

Besides Fergie and Andrew, Cory has no friend but Peter. The strange music she hears iin the night, the whispers of people in the town, and even the unicorns all weave a nightmare spell about Uncle Dirk and Grandmother that includes Cory, Laurel Woodford, the young woman on the beach, and Cory's stepmother. It is Cory who breaks the spell with the little unicorn amulet as the key.

Eleanor Cameron weaves her own special enchantment as a storyteller. Readers of The Terrible Churnadryne and The Mysterious Christmas Shell know it well."

Paperback edition:

Pocket Books, 1974, $0.75

A Spell is Cast