Any minute might bring the police.

Jack did not feel that he was to blame for what had happened, but he realized keenly that he was "in wrong" just the same, and he had no intention of languishing heroically in jail if he could possibly keep out of it.
He hesitated, and finally he went to the house and let himself in through a window whose lock he had "doctored" months ago.

His mother would not let him have a key.

She believed that being compelled to ring the bell and awaken her put the needful check upon Jack's habits; that, in trailing downstairs in a silk kimono to receive him and his explanation of his lateness, she was fulfilling her duty as a mother.
Jack nearly always humored her in this delusion, and his explanations were always convincing.

But he was not prepared to make any just now.
He crawled into the sun parlor, took off his shoes and slipped down the hall and up the stairs to his room.