Judgement of The Judoon by Colin Brake

Elvis the spaceport has become a huge success, growing into the sprawloing city-state of New Memphis and the Spaceport opens a new Terminal, Terminal 13. However this opening hasn't gone as expected, and things are about to get worse! When the Doctor arrives, he finds the whole terminal locked down. The notorious Invisible Assassin is at work again, and the Judoon troopers sent to catch him will stop at nothing to complete their mission. With the assassin loose on the mean streets of New Memphis, the Doctor is forced into a strange alliance. Together with teenage private-eye Nikki and a ruthless Judoon Commander, the Doctor soon discovers that things are even more complicated - and dangerous - than he first thought