Arriving in the Scottish highlands, Martin and Sue decide to escape their luxury hotel, heading out for a night of back-to-basics living in an abandoned shack. When a storm strikes, they find themselves stranded in the simple hut, miles from anywhere and completely isolated.

As gentle bickering leads to violent arguments, Sue starts to sense they are not truly alone - especially when a deep, dark presence seems to takes hold of the pair. With no way to escape, Sue and Martin must try to hold on to their sanity as the shelter quickly becomes a prison - and their thoughts begin to turn murderous...