Across the gulfs of time and space, the sixth Doctor discovers that his former incarnation is very much alive. Together with Peri and Jamie he must rescue his other self before the plans of Dastari and Chessene reach their deadly and shocking conclusion...
 

"WHEN YOU TRAVEL AROUND AS MUCH AS I DO, IT'S ALMOST INEVITABLE THAT YOU'LL RUN INTO YOURSELF AT SOME POINT."

When the Doctor (Colin Baker) lands on a space station in the Third Zone, he suspects he's been there before and when he discovers his old assistant - Jamie - he's certain.

Accompanied by Jamie and his present assistant Peri, the Doctor follows himself (Patrick Troughton) to 20th Century Seville. There he discovers his old enemied, the Sontarans, about to disect him in a genetic operation.

But just why are they operating on the Doctor? And how will their findings aid their enslavement of the Universe? Deadly questions to which the Doctors must find answers in order to escape their own excruciating death...