Character Arc
Joe Roag is an off-duty police officer who boards the sleeper train expecting nothing more than a few hours of broken sleep before Glasgow. Instead he finds himself thrust into the eye of a crisis, the one person on board with the instincts and training to confront a threat nobody can see. He is guarded and a little weary, a man carrying his own baggage long before the train ever leaves the platform.
As the hijack tightens its grip, Joe becomes the eyes and hands on the ground, relaying what he sees to the analyst on the other end of the line and trying to keep panicked strangers calm. His police instincts cut both ways, making him decisive in a crisis but slow to trust the very people he needs. The night forces him to confront how much he is willing to risk for passengers he has only just met.
By the finale Joe has been tested past anything in his service record, pushed into impossible choices where hesitation could be fatal. The crisis strips away his defenses and reveals the kind of officer, and man, he truly is when everything is on the line. His arc is the emotional spine of the series.