What does this quote mean? "The superintendent, a bundle of keys hanging from his belt, was standing at the door. Rodent and superintendent vanished into the lobby, only to emerge moments later, animal first."

I think this quote refers to A guard and a prisoner. The guard is the superintendent with the keys to the cell. He is standing by the prisoners door, and let the prisoner out into the lobby. I think the last part means that the prisoner got loose because he was first out the door.

Slow steady braking once car rolls back and comes to complete stop hard brake