eleven o'clock
They all took up their posts . Two detectives were to sit up in turns . This time , after making a minute search of the little room in which Fauville 's son used to sleep , they locked and bolted the doors and shutters . At eleven o'clock they switched off the electric chandelier . Don Luis and Weber hardly slept at all . The night passed without incident of any kind . But , at seven o'clock , when the shutters were opened , they saw that there was a letter on the table .