Josh Hartnett stars in a delightfully campy thriller.

If action movies had their own mythology, it would involve more hired assassins than your average corporate meeting. Apparently, these ninjas of chaos have a penchant for luxury hotels and the fine art of synchronized group travel, as showcased in “Bullet Train.” Now, a gaggle of these hitmen has decided to board a plane in James Madigan’s directorial debut, “Fight or Flight.” Here, Josh Hartnett gets yet another chance to remind us that he’s not just a relic of early 2000s cinema; he’s experiencing what some have dubbed the Hartnettaissance.

After a lengthy hiatus during which he seemingly perfected the art of being left off casting lists, Hartnett struts back onto the screen as a former government agent roped into a mission so dangerous it could only have been conceived during a sleepless night of too much caffeine and takeout. His charm and unexpected knack for physical comedy elevate the film from what could have been yet another B-movie fodder to something almost pretentious—at least until you notice the budget constraints and strange twists in tone.

For most of its runtime, the film is a frantic thrill ride that anyone who has endured the torture of cramped airplane seating will appreciate. The plot, which opens with a delightful appetizer of over-the-top violence, primarily unfolds within the unfortunate confines of a commercial flight that’s otherwise going to have a very boring destination.

Here’s the backstory you didn’t ask for: Lucas Reyes (Hartnett)—a washed-up agent who has transformed into a local beach bum—gets pulled back into action by Katherine Brunt (Katee Sackhoff), his boss, former lover, and now a CBD enthusiast struggling to keep calm amidst the insanity. They need him to catch The Ghost, a cyber-terrorist so stealthy that he seems more fictional than the plane itself.

Unfortunately, Reyes looks like he’s just taken a vacation from life, with a style that screams “I found this shirt in my dad’s closet.” But off he goes, sitting next to a seemingly friendly entertainer on the flight, who turns out to be less “seatmate” and more “potential assassin.” Spoiler alert: shockingly few people on this flight are there for the pretzels and peanuts.

What follows is a cavalcade of chaos as Reyes realizes he’s surrounded by would-be assassins all vying to take out The Ghost—and inevitably, him too. With the reliable help of Isha, a flight attendant played by Charithra Chandran—who jumps from “Bridgerton” to “Battleground”—and her amusingly panicked colleague, he takes on the entire plane full of hitmen in what is essentially the world’s worst in-flight safety video.

Madigan, who previously honed his skills in a second-unit capacity for big-budget blockbusters, makes the most out of this confined space, cleverly weaponizing every object that could potentially double as a makeshift murder tool. Talk about a missed market opportunity for in-flight merchandise sales!

The script by Brooks McLaren and D.J. Cotrona is a whirlwind of humor, as demonstrated when Reyes continues to take down opponents despite being loaded, high on psychoactive toad venom, and generally bewildered. Seriously, someone should take TSA out of the equation; they allow everything from guns to chainsaws on this flight—clearly, the in-flight security briefing has become a mere suggestion.

“Fight or Flight” is all about the fun—if you’re able to overlook the gallons of gore and don’t mind checking your sanity at the exit door. Hartnett’s willingness to go full chaos mode straddles the line between the tragic hero and the slapstick buffoon—making you wonder if action heroes are just as capable of turning life into a cartoon as any Looney Tunes character ever was. It’s a delightful mess, and it might just be your next guilty pleasure!