midnight
Guillot laughed derisively . `` As you please ! '' he exclaimed . `` By midnight to-night ! '' * * * * * 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 _ tête-à-tête _ dinner with his wife .