Ex policeman Robert and his wife Katy gave up their city lives after a witness in his care was shot dead, and he's been struggling with his guilt ever since. In an attempt to put the past behind them, the couple now run a guest house in the Lake District. But when old colleague DCI Maxwell suggests the building would work as a safe house, Robert takes in a family whose members are under threat. It's a chance for him to make use of his detective skills and ensure nothing goes wrong this time.