The Doctor and Donna land on a gorgeous snowy world -- your favourite alpine vistas, cranked up to 11--somewhere in the distant future. It is the Oodsphere, home planet of the Ood, the apparently willing slave race we first met in "The Impossible Planet"/"The Satan Pit". All is not well on the Oodsphere. Ood Operations, the Ood suppliers to the galaxy, are sitting on a disturbing fact: Ood everywhere have been going berserk and killing their masters. The only symptom is that the Ood's eyes will turn red just before it snaps.