five o’clock
The fact of the presence of the chambermaid -- who had come to clean up `` The Yellow Room '' -- in the laboratory , when Monsieur Stangerson and his daughter returned from their walk , at half-past one , permits us to affirm that at half-past one the murderer was not in the chamber under the bed , unless he was in collusion with the chambermaid . What do you say , Monsieur Darzac ? '' Monsieur Darzac shook his head and said he was sure of the chambermaid 's fidelity , and that she was a thoroughly honest and devoted servant . `` Besides , '' he added , `` at five o'clock Monsieur Stangerson went into the room to fetch his daughter 's hat . '' `` There is that also , '' said Rouletabille . `` That the man entered by the window at the time you say , I admit , '' I said ; `` but why did he shut the window ? It was an act which would necessarily draw the attention of those who had left it open . ''