Whitechapel Terminus (S03E01)

Four years have passed. Time that has seen Reid, Drake and Jackson split and isolated from one another. But when the robbery of a goods train leads to a cataclysmic locomotive disaster on Leman Street itself, the men and their resentments are reunited to seek its cause.

Meanwhile, Long Susan has made good on her promise to take control of Obsidian Estates, and has turned it into a legitimate business of huge philanthropic ambition. But such aspirations have a price - one which is paid by all those to lose their lives in the Leman Street Disaster. (BBC)