If you’re brazen enough to slap “A Comedy” on the cover of your novel, it had better be funny. Thankfully — for the reader, for the author, for everyone involved — Charles Baxter’s “Blood Test” is.

Take the opening lines: “Let’s say you stabbed yourself in the leg by accident. Let’s say you’re bleeding all over the floor.” Humor is famously subjective but it’s safe to say that, from the start, we’re in practiced and confident hands here.

That’s not surprising given Baxter’s track record. He’s a PEN/Faulkner winner and the author of six previous novels, including “The Feast of Love,” a finalist for the National Book Award in 2000. “Blood Test” proves to be a deft comedy — one with echoes of Charlie Kaufman and George Saunders — but it’s more than that, much more. I keep circling back to the phrase “minor classic” — maybe “quiet masterpiece”? — though I’m not sure why I need the qualifiers. Maybe it’s the book’s brevity (a svelte 209 pages) or the fact that, at first glance, the setup seems a tad familiar, maybe purposefully so. As with any successful knockout punch, part of its force is that you don’t see it coming.

Our hero is Brock Hobson, a wry and hapless middle-aged white guy who lives in Anywhere, U.S.A. (in this case, Kingsboro, Ohio). He has a troublesome ex-wife and two teenage kids who treat him with “lighthearted, ironic impatience that verges on contempt but never quite arrives there.” He’s steady. Reliable. Some might say — some do say — boring. As his daughter tells him early on: “You’re as predictable as a metronome.” In other words, he’s a type not underrepresented in the American canon, if not particularly in vogue.

After he’s persuaded to take a “predictive” blood test that, a doctor assures him, “tells you what you’re going to do before you do it,” he’s told that he’s got latent “antisocial tendencies” and that “felonies are definitely in your future.” Will Brock surprise his kids? Surprise us? Will he — dun dun dun — commit murder? The titular blood test is our inciting incident, though for Baxter it’s more like an ignition: He’s lighting the gas burner under a pot of water. The frog in the water is our hero. The boiling water is America.

The genius of “Blood Test” is how adroitly Baxter takes the measure of our moment, in all its insanity and perplexing depravity. While “Blood Test” is apolitical, it feels firmly anchored in the tumult of 2024. Brock’s ex-wife, Cheryl, and her troll-ish beau, Burt, are immersed in a cult called R/Q Dynamics that’s part Q-Anon, part Church of Scientology. Burt is the kind of man who “if you were to ask him where Italy is located on the globe, he wouldn’t know but would despise you for asking,” which perfectly captures a certain species of modern apoplectic online combatant.

Baxter throws a lot more into the pot as he brings it all to a boil. There’s Brock’s inscrutable progeny, living a version of operatic teen turmoil that feels both contemporary and timeless. There’s a visit by Brock to an emergency ward “crowded with sick people, and one person who looked unconscious from a dose of fentanyl, on top of the usual crowd of people who had fallen from ladders or had accidentally stepped barefoot on lightbulbs or slipped in the shower or had a dose of the latest designer disease,” a list that starts to feel Whitmanesque in its appraisal of American malaise.

There’s the occasional masterly turn of phrase, such as “the hee-haw of an ambulance.” There’s the appearance of a metaphorically resonant white rat. There’s an accident. There’s a wheelchair. There’s the introduction of firearms. There’s a duel! (What could be more American — more steeped in a bloody history of pride, bravado and idiocy — than a pistols-at-dawn duel?) There’s even room for a moment of transcendent beauty and grace, delivered in a dream by a dead mother from the afterlife. If Brock is the frog being boiled alive, Baxter is the scientist who expertly dissects that frog for our benefit.

By announcing itself a comedy, “Blood Test” isn’t wrong, but it undersells itself. It is a profound and unsettling — and, yes, frequently funny — snapshot of our current tribulations, cast in relief against the stubborn peculiarities of the American character.