- You may be looking for the Counter-Measures audio story.
Shortly after arriving on Earth in the 51st century, The Doctor and Izzy are greeted by Marquez, the android servant of Crivello, an aged scientist only kept alive by his complete immersion in a nutrient tank. Crivello is attempting to create an artificial sun for a new solar system for humanity after Earth is engulfed by solar flares. The Doctor discovers the sun is alive. Having built a rapport with the artificial sun, The Doctor orders it to travel to an unpopulated arm of the Crab Nebula to become humanity's new home.
After the Doctor and Izzy have left and humanity has gone to its new home, Marquez and Crivello are left alone on the dying Earth. As Crivello reflects on his accomplishment, Marquez abruptly kills the scientist and unceremoniously throws the body off a cliff overlooking the sea.
- Uber-Marshall Leng is a contemporary of Magnus Greel.
- Izzy throws up after being transmatted for the first time.
- This story was reprinted in Endgame.
- The events of The Keep are a prologue to COMIC: Fire and Brimstone.
- In TV: The Talons of Weng-Chiang, it was established that 51st century Earth was in an Ice Age and great national alliances like the Icelandic Alliance existed. The Keep instead has Earth ravaged by solar flares and states the rich left in a fleet of space arks, which — according to the account of TV: The Ark in Space — would occur some nine thousand years after the 51st century.