Doctor Who: Judgement of the Judoon by Colin Brake

The Doctor arrives in New Memphis, a spaceport formerly known as "Elvis the King Spaceport", which has grown into a vast city-state. It is set to open Terminal 13, but problems develop, and the Doctor faces a lockdown situation. A notorious criminal, the Invisible Assassin, is at large, and Judoon troopers are sent to apprehend him.