One fifth of the population of Earth dies at once – why? Epidemic? Weapon of mass destruction? Or is it little green aliens’ fault? In search of an answer a family couple, a surgeon and a forensic expert, even consider the latter, for the probability of the other answers is not much greater. Suggesting, analyzing and discarding one version after another, they gradually come to a completely different question: why the ones that survived were that lucky? Or – were they?