A: No one was injured in the fire after Jane led the audience to vacate the theater through the emergency exit.
B: Thank god! If Jane hadn’t kept her wits about her, things would have been much worse.
Note: This idiom means to “remain rational when threatened or under stress,” to “keep one’s mind operating in a time of stress.” Here, “about” means round about, close and near. If we liken our wits to our handbags or mobile phones it will make easy sense. If people keep their wits about them, it means they never lose their wits, which may come in handy, especially in tough situations where a quick decision needs to be made.