Louis Kehlweiler of the Three Evangelists trilogy returns, along with his beloved pet toad, Bufo. Vauquer Clement, a young accordionist in his thirties has disappeared, believed by police forces from Nevers to Paris to have killed two women, both shockingly violent murders. But Kehlweiler is not so sure he's guilty. With his team of experts, he must go back and look at all the facts, and see if he can clear Clement's name before it's too late.