You go upstairs and go to bed comfortably.

I'll make a careful search of the house before I settle down, and if I find anything at all suspicious, I'll promise to let you know." She agreed to that, and after sending the Jap out for more coffee prepared to go upstairs.
Never had the thought of her own comfortable bed appealed to her so much.

But, in spite of her weariness, she could not quite resign herself to take Lizzie's story as lightly as the detective seemed to.
"If what Lizzie says is true," she said, taking her candle, "the upper floors of the house are even less safe than this one." "I imagine Lizzie's account just now is about as reliable as her previous one as to her age," Anderson assured her.

"I'm certain you need not worry.

Just go on up and get your beauty sleep; I'm sure you need it." On which ambiguous remark Miss Van Gorder took her leave, rather grimly smiling.
It was after she had gone that Anderson's glance fell on Brooks, standing warily in the doorway.
"What are you?
The gardener ?" But Brooks was prepared for him.
"Ordinarily I drive a car," he said.