When the metal is hot and the engine is hungry
So he wasn't exactly a prisoner. He wasn't shackled in one of the cells, aka the detention rooms, or confined to his room in the adult wing. He wasn't barred from mixing with the students, although he was sure that he was being monitored. No one could say he wasn't cooperating fully with the program.

Except he was sure he was going crazy. He needed off the estate, he needed news about his family, and he needed to lose the tension. So he did what any self-respecting adult would do in his situation. He sneaked out to give himself a break as a reward for good behavior.

He pushed his old motorcycle to the front gate and prepared to take off for a few hours. It didn't matter where. To the city to get a few things and drive Darlene back. He wouldn't see Mom, no need to worry about another attempt at either of their lives. To Harry's for a couple of beers before last call. The barmaids would be safe.

Somewhere that wasn't Here.