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 has been messing with technology that's not of this earth, blurring the lines between human . . . and cyber. And it looks like they're out for revenge.

In a world on the brink of gadgets and gismos and dangerous tech, the pair must uncover the killler, before they strike again.