Doctor Who 80s book

Midnight, 1984.

In a sprawling, run-down housing estate in south London, a man returning from a night out in the West End finds himself pursued by a strange hooded figure.

So naturally when the Doctor and Romana arrive in the TARDIS the next day, they find themselves in the middle of a crime scene.

But when child genius Matthew Pickles - inventor of a hugely popular handheld videogame - arrives to help them crack the case, they discover there is more to this than meets the eye.

Someone ...