It’s a crime tailor-made for the Peculiar Crimes Unit: a controversial artist is murdered and displayed as part of her own outrageous installation. No suspects, no motive, no evidence – it’s business as usual for the Unit’s cantankerous founding partners, Arthur Bryant and John May. But this time they have an eyewitness. According to twelve-year-old Luke Tripp, the killer was a cape-clad highwayman atop a black stallion.

As implausible as the boy’s story sounds, Bryant and May take it seriously when ‘The Highwayman’ is spotted again, striking a dramatic pose at the scene of his next outlandish murder. Whatever the killer’s real identity, he seems intent on killing off a string of minor celebrities while becoming one himself.

As the tabloids look to make a quick bundle on “Highwayman Fever”, Bryant and May, along with the newest member of the Unit, May’s agoraphobic granddaughter, April, find themselves sorting out a case involving an unlikely combination of artistic rivalries, sleazy sex affairs, the Knights Templars, and street gang feuds. To do it, they’re going to have to use every orthodox – and unorthodox – means at their disposal, including myth, witchcraft, and the psycho-geographic history of the city’s “monsters”, past and present.

And if one unsolvable crime weren’t enough, this case has disturbing links to a decades-old killing spree that nearly destroyed the partnership of Bryant and May once before…and may again. The Peculiar Crimes Unit is one murder away from being closed down for good – and that murder could be their own.