Doctor Who: Shakedown: A 7th Doctor novel

For thousands of years the Sontarans and the Rutans have fought a brutal war across the galaxy. Now the Sontarans have a secret plan to destroy the Rutan race—a plan the Doctor is racing against time to uncover. Only one Rutan spy knows the Sontarans’ plan. As he is chased through the galaxy in a desperate bid for his life, he reaches the planet Sentarion—where Professor Bernice Summerfield’s research into the history of the Sontaran-Rutan war is turning into an explosive reality.