Following a brutal attack by her ex-boyfriend, Kate Priddy makes an uncharacteristically bold decision after her cousin, Corbin Dell, suggests a temporary apartment swap - and she moves from London to Boston. But soon after her arrival Kate makes a shocking discovery: Corbin's next-door neighbour, a young woman named Audrey Marshall, has been murdered. When the police begin asking questions about Corbin's relationship with Audrey, and his neighbours come forward with their own suspicions, a shaken Kate has few answers, and many questions of her own. Jetlagged and emotionally unstable, her imagination playing out her every fear, Kate can barely trust herself. so how can she trust any of the strangers she's just met?