Trailer
The forty-second trailer features Donna Noble, portrayed by comedienne Catherine Tate, sitting over a camp fire, talking about "creatures of metal, fire, and blood" threatening the universe as shots of the Daleks, Sontarans, and the Ood come into view. She talks about a man called the Doctor (David Tennant), who is portrayed in fleeting glimpses until his name is mentioned, who constantly saves the universe from these threats. Donna ends her narration by saying the Doctor will be back to save them and she will be ready to join him. The trailer ends with the Doctor and Donna simultaneously saying "and just like that, we'll be gone."
Read more about this topic: Doctor Who (series 4)