After the death of her twin sister, Lucy, and a subsequent breakdown, Abi is haunted by memories. One day she meets Bea – a girl with an uncanny resemblance to Lucy – and Bea's twin brother, Ben, with whom she feels an irresistible attraction. Bea invites Abi to live with them, which places Abi's relationship with Ben under strain. But Bea has a secret that she'll do anything to hide...