Watch Doctor Who: 12×4

Nikola Tesla's Night of Terror

1903. On the edge of Niagara Falls, something is wrong at Nikola Tesla’s generator plant. Who or what is sabotaging the maverick inventor’s work? Has he really received a message from Mars? And where does his great rival Thomas Edison fit into these events? The Doctor, Yaz, Ryan and Graham must join forces with one of history’s great minds to save both him and planet Earth.