It's the ultimate in mass transit systems, a network of interstitial tunnels that bind the planets of the solar system together. Earth to Pluto in forty minutes with a supersave non-premium off-peak travelcard.

But something is living in the network, chewing its way to the very heart of the system and leaving a trail of death and mutation behind it.

Once again a reluctant Doctor is dragged into human history. Back down amongst the joyboys, freesurfers, chessfans, politicians and floozies, where friends are more dangerous than enemies and one man's human being is another's psychotic killing machine.

Once again the Doctor is all that stands between humanity and its own mistakes.

Ben Aaronovitch wrote Remembrance Of The Daleks and Battlefield, two of the most highly regarded Doctor Who stories of recent years; his novelization of Remembrance of the Daleks was rapturously received. He lives in north London and is, he says, not half as interesting as he would like to be.