Ursula Moray William's uncanny imagination shifts from the Toymaker's Bavarian forest to the more congenial confines of England's Castle Merlin -- in medeival times the home of falconer Lady Alys Hemingway, now the site of a Holiday Club excursion. While the other young vactioners play at being Kestrels, Harriers and Merlins, Susie encounters a number of mysterious and melancholy individuals -- a prisoner wasting away in the dungeon, the girl Alice who sleeps in the next bed and has a very unusual wardrobe, and finally Lady Alys herself (""We have been you. You have never yet been us...You ought to try to understand us and be kind about it.""). Susie's friend Bryan (himself something of a puzzle -- he can neither read nor write) is at first determined to rescue the man in the dungeon, but though the children find they can't really help the Castle's phantasmic residents -- just the experience of seeing them is unforgettable. Susie eventually returns home to a reassuring domestic reality, but the open ended spookiness of her castle adventure will continue to haunt those who believe in ghosts, or have always wanted to.