Another regeneration, but this is unlike any other The Doctor has experienced. The Doctor is disoriented, confused, and begins searching his TARDIS for the "Zero Room" (a form of meditation chamber that aids with post-regeneration sickness). Later, one of The Doctor's companions, Adric, is kidnapped by The Master, and The Doctor realises that his plan is far more intricate than originally believed - and it also threatens to destroy his mind...
