He was certain that he had never been to this house, and 'he' had not been to this house in the surveillance cameras last night. Then, this should be the first night he stayed in this house. He had come here after waking up.
What was in this house?
Zhuang Long followed the footprints and walked in. When he reached a wall, he stopped. He had already reached the end, but the footprints turned around and walked out of the house. There must be a reason why 'he' came to this house. It was impossible for him to specially come in and walk around before going back.
Zhuang Long stood by the wall and sized up the room many times.
He did not discover anything unusual.