When Peter Grant’s young cousin, Abigail Kamara, drags him and his colleague and fellow magical apprentice, Leslie May, to a railroad track running under a school playground, they do find the ghost. But the ghost is no threat, and doesn’t seem to be pointing to anything of concern now. So when the first case that lands on his desk on Monday is a man stabbed to death on the track at Baker Street Station, he puts the ghost aside, and sets about finding out why the British Transport Police officer, Sgt. Kumar, thinks there’s something odd about the case in a way that makes it the Folly’s business.
The young man on the tracks, James Gallagher, was indeed killed by a magic-imbued weapon, and he is, inconveniently, the son of a US Senator. The weapon was a broken portion of plate, of an unfamiliar make called Empire Pottery. When they go to the young man’s home in London, they meet his housemate, a rather flighty and odd young man named Zachary Palmer, and see a figurine that matches the broken shard James was killed with, and which is also imbued with magic. Zach can show them where James got the figurine–but not immediately. The market is closed.
In the meantime, there’s the question of how James got to where he was found, since none of the monitor cameras caught him going into either Baker Street Station, or any plausible nearby stations. Sgt. Kumar concedes there are secret entrances to the system, but not, he says, secret from the BTP, he says. That would be a terrible idea.
Peter finds himself assigned to the murder team investigating James Gallagher’s murder, to roughly equal distress on his side, and the murder cops who have never worked with the Folly before. He’s also soon working with FBI Special Agent Kimberly Reynolds, a conservative Evangelical who does not regard magic positively. (Fortunately, Aaronovitch is far too good a writer to make her stupid or comical.)
Soon Peter’s problems include the pottery company which is a small part of a construction company, a dealer in goods of sometimes questionable origin, who are Zach’s unloving family because he’s the product of an affair with, apparently, one of the Fae, some of Mother Thames’s daughters, a visiting Taiwanese magic practitioner, and a whole town, possibly a city, living in the secondary and unused tunnels of the London underground.
The diplomacy needed to interact successfully with the river goddesses; the underground fae city; an Evangelical FBI Special Agent who is following US law enforcement rules on carrying, pulling, and using her gun – none of this is what Peter thought he was signing up for when he let himself be recruited into magic and the policing thereof on the strength of his ability to see ghosts. Working with a murder investigation team that has never worked with the Folly before and is understandably both skeptical, and averse to the Folly’s negative effect on case clear-up rates is also a challenge, if a more mundane one.
It’s a challenging case, in which Peter learns more about the magical population of London, magic itself, and his own mind. We also see Leslie May, the other apprentice wizard, who is still adjusting to living with her damaged face, and starting to learning that the people of the magical world look at her maskless face, and don’t care. This might have repercussions in later stories.
All in all, a very good story, with characters who continue to grow.