As the shadows rise and march, the Doctor forges an alliance with the mysterious River Song, as Russell T Davies's Bafta Award-winning time-travelling drama continues. But can anyone stop the Vashta Nerada?

While the Doctor discovers long-buried secrets and revelations about his own future, the sinister Nodes declare that Donna is doomed.

David Tennant plays the Doctor and Catherine Tate plays his companion, Donna. Alex Kingston, Colin Salmon and Steve Pemberton guest star.