July Books 4) Harvest of Time, by Alastair Reynolds
"We are what we are, Doctor. If I did not exist, the universe would soon fill the void left by my absence. You could almost say that the universe requires us. We are order and disorder. We balance each other very effectively."
This wheeze of getting well-known writers to contribute new Doctor Who books is proving an awfully good adventure. This is an excellent Doctor/Master/Jo story with UNIT in a supporting role, with adventures on oil rigs and a brilliant time paradox which poses an existential threat to the Master, and through him to the universe - very neatly done, and the Doctor is forced to make a crucial choice about his old enemy. Reynolds has caught the spirit fo the Pertwee era and made something new out of it. Strongly recommended both for Who fans and Reynolds fans. (Many of the latter are already in the former category, of course.)