The narrative centers on the forgotten planet Shada, where the Time Lords constructed a facility to incarcerate vanquished aspirants of universal domination. Skagra, a former prisoner, seeks assistance from one of the inmates. However, the location of Shada has been lost to time, with only an elderly Time Lord, now living on Earth as a professor at St. Cedd’s College, Cambridge, retaining the knowledge. Fortuitously for the cosmos, Skagra’s effort to extract this information from Professor Chronotis happens to align with a visit from the professor’s longtime acquaintance, the Fourth Doctor.