The Unnatural Inquirer by Simon R. Green (First Edition)

John Taylor's the name. I'm a PI, working that small slice of mystical real estate in the hidden centre of London that's called the Nightside. It's a place where the sun refuses to rise, where monsters and men walk side by side, and where you can fulfill your every dark and depraved desire. What I do there, better than anybody else alive (or dead) is find things - for the right client, for the right price.
My new client can certainly afford me. The editor of the Unnatural Inquirer, the Nightside's most notorious gossip rag (the one everyone pretends not to read), has offered me one million pounds to find a man named Pen Donavon, who claims to have evidence of the Afterlife - picked up on a television broadcast and burned onto DVD. The Inquirer made Donavon a sweet deal for exclusive rights. Then both he and the disc vanished.
I don't know if the disc is on the level, but a job's a job (and a million pounds is a million pounds). Trouble is, not only are all of the usual suspects pretty dangerous individuals, but it's beginning to look like someone else - someone very powerful - is on the trail, too. And who - or what - ever it is, is deadly determined to find the disc first.