You’ve known her all your life... Or have you?

Tasha and sister Alice look alike, but couldn’t be more different.

Tasha’s married with kids, settled near their home town of Bristol. While Alice travels the world with her husband. Yet each trusts the other with her life.

So when Tasha wants a break, Alice offers to stay in her home with the kids, so her sister can have a holiday. Tasha knows they’re in safe hands. She couldn’t be more wrong.

The call sends Tasha rushing home. Alice is in intensive care. Her husband is dead.

The police are hunting for suspects and motives. But Tasha can’t think why anyone would hurt her sister. Then the note arrives, addressed to Tasha: It was supposed to be you .