Yes, that's my game.

I want to get into his rooms whilst he is sleeping, and be free to search his effects.

I want to get into every man's room here, and wherever I find poison--well, you understand ?" "Yes," he replied, brightening as he grasped the import of the matter.
"What a ripping idea! And so simple." "I think so.

Once let me find the poison, and I'll know my man.

Now one other thing: the housekeeper must have a master-key that opens all the bedrooms in the place.