Mel searches for the Doctor and runs into a indigenous life form and has to explain that she is looking for The Doctor who may be able to help his people, meanwhile the Rani works to keep the Doctor convinced that she is Mel so he will help her with her plans.

The Doctor gradually starts recovering from his regeneration and begins to piece together the Rani' plan after finding the real Melanie. He then discovers that the Rani has taken the greatest minds in history and brought them all together to complete the mathematical calculations related to her nefarious plan to take over the universe.