Doctor Who Shakedown by Terrance Dicks

This compilation of texts follows multiple interconnected plotlines. It begins with a con artist named Kurt whose smuggling operation is thwarted, leading him to encounter a mysterious figure, the Doctor, and become entangled in a Sontaran occupation. Meanwhile, the Doctor's companions, Roz and Chris, are on a different planet, Megerra, pursuing a shapeshifting Rutan serial killer known as the Ripper. A third narrative thread introduces Bernice Summerfield arriving on Sentarion for academic research, only to find herself trapped and in danger due to a sinister secret connected to the planet's ancient history and its insectoid inhabitants. These disparate threads converge as the characters eventually meet on Sentarion, becoming embroiled in a conflict between the Sontarans and the Rutan, with the planet's unique history playing a crucial role.