The Boggart - Susan Cooper

Accidentally transported from his remote Scottish castle to the bright, fast-moving, hi-tech city of Toronto, the highly mischievous Boggart simply can''t resist the opportunity for pranks, and wreaks havoc for the Volnik family, inheritors of his distant castle home. But the Boggart doesn''t mean any real harm, and when he begins to pine for the rolling Scottish mists and the sound of bagpipes, he turns to his two young friends, Emily and Jessup Volnik, for help.