Alice and Cecily haven't been in touch for years. A difficult childhood with an abusive, domineering father and the tragic death of their brother meant that at 16 they went their separate ways. But Cecily has sent a letter, pleading for Alice's help.

Cecily's marriage is in difficulty. She needs time out to get herself together and to approach a solicitor. If Alice could take her place in the family home for just a week, that's all she needs.

Alice agrees and, with instructions from Cecily on all that's needed to impersonate her identical twin sister, she seems to make a convincing swap.

But has Cecily told her the truth? Is everything as it seems? What does Cecily really want to achieve with her sister in her place?

This is a gripping thriller which keeps you guessing throughout, and a great twist too!