With a novel called “Noir,” there are certain elements that are expected. A hard-boiled (male) detective, ideally named Sam, for one. A dangerous dame with a mysterious past. Add in murder with a cast of quirky side characters set in early-20th century San Francisco, and the mystery basically writes itself. Christopher Moore covers all his noir fiction bases as his latest novel incisively and delightfully lampoons the genre. Set after World War II, “Noir” follows bartender Sammy “Two-Toes” Tiffin on a ridiculous adventure to make some money, solve the mystery, and get the girl. Plus, there are aliens.

From the get-go, there is no question what kind of book “Noir” is going to be. From its extraordinarily on-the-nose title to the first line of the first chapter, in which Sammy describes his love interest—a woman he calls “the Cheese”—as having “the kind of legs that kept her butt from resting on her shoes,” the novel establishes an irreverent 1940s-style voice that characterizes the narrative and furthers the satirical element. Though the narration itself jumps around between Sammy’s first person and a mysterious narrator who remains unnamed until the end and whose chapters effectively read like a third person narrative], every chapter is consistently full of humor and tough-guy moments like Sammy’s description of his manly scream: “The scream of a fellow who has caught his enormous dong in a revolving door while charging in to save a baby that was on fire or something.”

Moore’s prose is snappy and clear, littered with silly word choice (notably, the phrase “phonus bolognus” is used several times) and snarky asides: “It is well known that all North Beach dogs bark in Italian.” He navigates the genre and period he takes on with ease and authority, seamlessly weaving period-appropriate slang and an undeniably extensive knowledge of San Francisco geography into the narrative, immersing the reader completely in Sammy’s world.

For all that “Noir” mimics the early 20th-century crime fiction of Dashiell Hammett and Raymond Chandler, it is still a modern novel. Though Sammy and the Cheese are both young, white, and heterosexual, the book’s notably diverse supporting cast is littered with a wide sampling of the minority groups living in San Francisco in the 1940s. Sammy’s Chinese best friend, Eddie “Moo Shoes” Shu, their African-American friend Lone Jones, and the drag club-owning, men’s clothes-wearing butch lesbian Jimmy Vasco are all presented as complex, multi-dimensional characters. Their “otherness” reflects the historical realities of the time, but the characters themselves are far from stereotypical.

While the novel’s foundation and voice are both exquisitely rendered, the novel’s plot (particularly its resolution) falls short. What begins with a money-making venture involving a poisonous snake rapidly devolves into a complex and somewhat confusing government plot regarding three “moonmen” who have crashed their UFO in New Mexico. There’s a secret organization of wealthy San Francisco men who meet in the woods to perform rituals dressed as women and an even more secret government agency that goes head-to-head with Sammy, the Cheese, and the rest of the gang. This weird alien plot, though it stands in stark contrast to the intensely realistic voice of the novel and the first half of the action, could have been an effective and amusing addition to the satire if not for the way it forces Moore to wrap up the story. In order to tie up all of the loose ends of an exceptionally complicated narrative with an enormous cast of characters (almost all of whom, it should be noted, are impressively distinct and well-developed), Moore spends many of his last pages using dialogue to “tell, not show” and hastily explain all of the mysteries. The ending is neatly tied up with a bow in a way that feels both unsatisfying and incongruous with the complex, masterfully woven first 250 or so pages.

Fast-paced, engaging, and, hilarious, “Noir” captures the essence of the noir subgenre and then turns it on its head. It presents the dark underbelly of 1940s San Francisco with a lightness and cleverness readers have come to expect from Moore, drawing the reader into this post-war world of seedy bars, g-men, and all-night diners that celebrate the New Year year-round. Moore paints a picture of the world after Prohibition and World Wars—a world of uncertainty. Uncertainty about where your next paycheck will come from, who you can trust, and why there are aliens in New Mexico anyway.