four minutes
before seven
`` As you please ! '' he exclaimed . `` By midnight tonight ! '' The challenge of Monsieur Guillot was issued precisely at four minutes before seven . On his departure , Peter spent the next half-hour studying certain notes and sending various telephone messages . Afterwards , he changed his clothes at the usual time and sat down to a tete-a-tete dinner with his wife . Three times during the course of the meal he was summoned to the telephone , and from each call he returned more perplexed .