My name is Peter Grant, police officer, apprentice wizard and well dressed man about town. I work for ECD9, otherwise known as the Folly, and to the Murder Investigation Team as 'oh god not them again.' But even their governor, the arch sceptic and professional northerner DCI Seawoll, knows that sometimes, when things go bump in the night, they have to call us in.

Which was why I found myself in an underground station at five o'clock, looking at the body of James Gallagher, US citizen and Arts Student. How did he avoid the underground's ubiquitous CCTV to reach his final destination, and why is the ceramic shard he was stabbed with so strongly magical?

As the case took me into the labyrinth of conduits, tunnels and abandoned bomb shelters that lay beneath the streets I realised that London below might just be as complicated and inhabited as London above.

And worse, James Gallagher's father is a US senator, so the next thing I know, I've got Special Agent Kimberley Reynolds of the FBI "liaising" with the investigation and asking awkward questions. Such as 'just what are you guys hiding down here' and 'how did you conjure that light out thin air?'