In 2003, Rebecca Whitaker died in a road accident. Her husband Mark is still grieving. Then he receives a battered envelope, posted eight years ago, containing a set of instructions and a letter with a simple message: "You can save her." Later that night, while picking up a takeaway, Mark glances at a security monitor - to see himself, standing in the restaurant in grainy black and white. And behind him there's a stone statue of an angel. Covering its eyes, as though weeping... except, when Mark turns, there's nothing there. As Mark is given the chance to save Rebecca, it's up to the Doctor, Amy, and Rory to save the world. .