Detective Caius Beauchamp is dispatched to a double murder in a South London townhouse. It looks like a simple botched burglary, until Caius gets a tip-off about the well-heeled family's nefarious past. Which is worse: the body on the floor or the skeletons in the closet? Caius' own family circumstances have changed recently: some complicated inheritance tetris means he is now in line to inherit a country estate. He's still getting used to his new life in the upper echelons of society. And when he realises that he recognises the victims from a recent luxury train ride, it all starts feeling a little too close for comfort.