Doctor Who Series 4 - Turn Left Trailer

On the planet Shan Shen, Donna meets a mysterious fortune teller. The woman persuades Donna to reveal the events which culminated in her original meeting with the Doctor -- and then Donna’s world suddenly changes, as those very events are undone. Now Donna Noble lives in a world without the Doctor: a world in which London is destroyed by the spaceship Titanic, America is devastated by the Adipose, and the entire planet is nearly annihilated by the Sontarans. Only an enigmatic blonde traveller from a parallel universe can help Donna restore the original course of history, and prepare her to face the oncoming darkness.