Book excerpt: Welcome to the Metrozone -- post-apocalyptic London of the future. While the rest of Britain has devolved to anarchy, the M25 cordon protects a decaying city filled with homeless refugees, street gangs, exiled yakuza, crooked cops and mad cults. And something else; something new and dangerous. Enter Samuil Petrovitch: a Russian émigré with a smart mouth, a dodgy heart and a dodgier past. He's brilliant, friendless, cocky and -- armed only with a genius-level intellect, prototype cyberware and a prodigious vocabulary of Russian swear words -- might just be most unlikely champion a city has ever had. Welcome to the future. Mind the gap.