The servant responded in a panic, "Yes, indeed. Cosmo finished dinner, and I cleared the dishes. He should have gone downstairs from the terrace behind the study and left through the backyard.

I saw that the balcony door of the study was open. It was originally locked, so I don't know how it got unlocked."

Suddenly, something dawned on her. "I remember now. Mr. Walker came in the evening. After dinner, he said he wanted to choose a bedroom to take a shower and rest, so he took the keys to several rooms with him.

He must have opened the door to the study and didn't lock it again, allowing...