(Reuben is lying there.)

DOCTOR: Rigor mortis.

LEELA: What is that?

DOCTOR: He's been dead for hours.

LEELA: But that is not possible. He was in his room.

DOCTOR: Not Reuben.

LEELA: But he was! I saw him.

DOCTOR: The chameleon factor, sometimes called lycanthropy. Leela, I've made a terrible mistake. I thought I'd locked the enemy out. Instead, I've locked it in, with us.