In a panic, Zoe wakes Jamie and informs him that the Doctor is missing. They search throughout the TARDIS, but find no sign of him. He just disappeared from his laboratory. They are startled to hear knocking on the TARDIS door, as they are travelling in the Vortex. Thinking it might be the Doctor, they use the TARDIS force field to protect themselves and open the door. It is not the Doctor, but a stranger. They bring him inside. The stranger, whose name is Vorac, tells them he is a Time Rider, a species that travels the time winds of the Vortex. He has been separated from his pack.