Tasha has always felt in the shadow of her older sister, Alice. Their lifestyles couldn't be more different; Alice is married to wealthy entrepreneur Kyle and has a high-flying career, Tasha is married to her childhood sweetheart and lives in a Bristol suburb with their four-year-old twins. When Alice realises that Tasha is struggling - with money, the kids, losing her identity - she suggests they do a lifeswap for a week. Alice and Kyle will come to stay at Tasha's terraced house to look after the twins, while Tasha and Harry spend the week in Alice and Kyle's Venice apartment.

But a few days in, it all goes terribly wrong. Tasha receives a phonecall to say Alice is in hospital and Kyle is dead after an intruder broke into their house. They think it must have been a burglary gone wrong. Until a note arrives through the letterbox saying It was supposed to be you. Who was there that night, and why? Is it really Tasha they are targeting? And can these two sisters find the answers they need, or are they about to stumble upon something more sinister?