When a completely new team arrives at the Pontypandy fire station, Chief Fire Officer Boyce looks for a suitable leader. He finds what he's looking for in a local living legend. He believes that he will be able to create a good team, but he does not know that Sam has changed after all these years. He was still irreplaceable in his profession, but as a dry and cold man, he became a shadow of himself. Will the young firefighters be able to restore meaning to his life? And will they be able to find those who made this team before them? Can what separated them bring them together again? The path to mystery unites the new team more than the best exercises as they hide from each other, finding one behind the other. But one person has moved farthest away, and will there still be a place for him in Pontypandy? And won't betrayal prevent the young firefighters from searching?