Following a brutal attack, Kate Priddy makes an uncharacteristically bold decision after her cousin, Corbin, suggests a temporary apartment swap - and she moves from London to Boston. But soon after her arrival Kate makes a shocking discovery: Corbin's neighbour, a young woman named Audrey, has been murdered. When the police begin asking questions about Corbin's relationship with Audrey, a shaken Kate has few answers, and many questions of her own... A new start - or a perfect nightmare?