Doctor Who: Cat's Cradle - Time's Crucible(1992)

Marc PlattPeter ElsonTerrance Dicks

'You’re on your own, Ace.'
          The TARDIS is invaded by an alien presence, and is then destroyed. The Doctor disappears. Ace, lost and alone, finds herself in a bizarre deserted city ruled by the tyrannical, leech-like monster known as the Process.
          Lost voyagers drawn forward from Ancient Gallifrey perform obsessive rituals in the ruins. The strands of time are tangled in a cat’s cradle of dimensions. Only the Doctor can challenge the rule of the Process and restore the stolen Future.

But the Doctor was destroyed long ago, before Time began.