The inventor Sir Claude Amery wants to give the thief of the formula for his latest invention the chance to return it in the dark without being recognized. He gathers everyone in the house in the library and has the lights switched off for a short time. When the light comes back on, Amery is dead. A case for the Belgian master detective Hercule Poirot.

What to do if you are stuck as a police officer in a boring small town, no decent crimes happen and you should actually make the big career at the instigation of your wife? In this lamentable situation is Heinrich Karpf. An unfine plan is supposed to bring about the change: where there is no spectacular case, one must be faked...