After the events what happened in Wiltshire, England, Missy, Suki and the Doctor go into hiding, with Suki now has regenerated into a new body despite being human. They are unaware that Omega is alive and carrying on with his experiment that can destroy all life on Earth, Only Missy's past is the key to finding out how to stop Omega once and for all. However thanks to Omega's Experiment on Suki life hangs in the balance as her body starts to reject the regeneration vile that could end her new form.