WHEN REMOVED FROM its context, the subject matter of fantasy novels often sounds patently ridiculous. This can be a hurdle when reading reviews of the genre, but I'm hoping that once you've read the sentence I'm about to write about Jeff VanderMeer's new novel Finch, we can all just move past it together. So: Finch is a detective story about time-traveling sentient mushrooms who take over a city. Okay? Okay.

VanderMeer's premise is a viscerally unsettling one: The beautiful, ruined city of Ambergris has been overrun by malevolent fungal creatures called "gray caps," who control the human population with the bizarre mushroom-based weapons in their arsenal. Fungi colonize buildings and bodies, turning houses to mush and streaking human skin with fungal stains that look like birthmarks. Humans are utterly in thrall to the gray caps. Writes one character:

"I could disguise myself from the gray caps, but not from their servants—the spores, the parasites, the tiny mushroom caps, fungi, and lichen. They found me and infiltrated me—I could feel their tendrils, their fleshy-dry-cold-warm pseudopods and cilia and strands slowly sliding up my skin, like 100 tiny hands."

The titular Finch is a detective, tasked with solving the murder of a human and a gray cap whose bodies were found together in an apartment building. His work on the case unexpectedly leads to a collision with his own past, and with the underground movement dedicated to overthrowing the gray caps' regime once and for all.

Finch can be tough to parse, at times—in addition to the giant talking mushrooms, there's a lengthy backstory involving Finch and the city's history. And VanderMeer's prose mimics the hard-boiled detective novel, biting off sentence fragments, rarely letting a complete sentence unfold—a device that, while largely effective, can grate at times. All of this pales, though, alongside the truly weird, original world VanderMeer creates here, and the haplessly human character he's created to navigate it.

VanderMeer reads at Powell's on Saturday, but the real action is at the signing party at the Press Club, where VanderMeer will be joined by Jeff Johnson (author of Tattoo Machine, about his time working in Portland tattoo parlor the Sea Tramp), Jay Lake, and Fantasy Magazine co-editor Cat Rambo.