There are actually a couple of Moy Castles, but this one is located on the Isle of Mull. It was owned by the MacLaines who were considered the unruly part of the MacLeans.
The story goes that the MacLean of Duart wanted Lochbuie, so he captured a MacLaine and imprisoned him to prevent his production of an heir. The MacLaine still managed to impregnate his jailor, an old ugly woman, who then produced a son and heir to the lands.
The tower is a 15th century keep with three floors. Hector, the brother of Lachlan MacLean, is assumed to have built it. A garrison was placed here in 1690 by the Earl of Argyll to help with the Jacobite uprising. It was abandoned in 1752 in favor of a larger and more comfortable house.