(In the control room, the Doctor is clearly weakening. He leans against the console and operates the door control; Ben and Polly burst in to see him stagger past the console and lean forward. The TARDIS controls are now working themselves; the door closes and the central column begins moving up and down. The Doctor's body is wracked by some huge inner turmoil; he struggles to stay on his feet, but the effort is too much for him. He collapses.)
POLLY: Doctor! Quick, help him!
BEN: No, leave him!
(Ben points at the unconscious Doctor. The old man is lying on his back, totally still, his face expressionless. As they watch, a strange glow comes over the Doctor's face; the glow brightens to a brilliant white, then fades. And the face which is left behind is that of a total stranger...)