Holly feels rejected. Her cool, remote mother has dumped the thirteen-year-old on an aunt and uncle she barely knows, at a farm in southern England. Holly takes her flute to her aunt and uncle's old barn, and the notes of her instrument set off a mysterious hum from the back of the building.

Perhaps she shouldn't have gone to investigate the sounds. Maybe she shouldn't have moved the pile of broken-down farm implements that blocked her path. But how else was she going to get that ancient-looking door open?

Besides, somehow Holly can't help herself...