The third series of this riveting crime drama opens with a cataclysmic event which reverberates throughout the series. Fifty-five souls are lost to a terrible locomotive disaster, with the wreckage landing right in the lap of 'H' Division - on Leman Street itself. From the twisted debris of the crash emerge clues that uncover long hidden deceits. These crimes threaten not only to destroy Reid's iron grip on 'H' Division, but to unravel his fragile psyche too. The personal damage to Reid is profound and there is no limit to what he will do to avenge his own, deep-seated grief.