After visiting the castle in Scotland which her family has inherited and returning home to Canada, twelve-year-old Emily finds that she has accidentally brought back with her a boggart, an invisible and mischievous spirit with a fondness for practical jokes.

Allie, Jay, the Boggart, and his cousin Nessie strive to stop an American developer from destroying their home, even if that means waking up deadly Old Magic creatures.--Provided by Publisher.