A young girl calling herself Mary Gray receives an unexpected and, at first glance, crazy offer - to pose as a wealthy heiress, the granddaughter of the owner of the Whitescar estate, who disappeared eight years ago, and whom she bears an uncanny resemblance to. So, at least, says estate manager Connor Dermott, who made her this proposal. Mary Gray agrees to participate in a dangerous adventure. However, the goals she pursues are directly opposite to those that Connor is trying to achieve.