On location in Scotland for a film shoot, stuntwoman Cat Terril is waiting to film an action scene when it takes a stroll though the ancient castle that is their set.
Then she meets an old man in black robes who gives her a set of keys and directs her to "Follow your heart...."
Thinking it is a harmless prank designed by fellow stuntmen, Cat follows the old man's direction to a locked door around which swirls a strange lavender mist.

Using the set of keys, she opens the door, steps into the mist and falls literally into a frigid lake in thirteenth century Scotland.

There was no harmless prank involved. Cat is in desperate peril, finding herself suddenly the hostage of viscous, brutal clan leader Calum MacKay. To obtain clemency from the Scottish king, the renegade MacKay must give his daughter Brianna to Englishman Roderick de Montwain in marriage. Brianna, however, in love with another, has run away and Cat bears a striking resemblance to MacKay's absent daughter.