For a guy like Glen Powell, the ascent to movie stardom isn’t really a question. It’s more like an inevitability.

Blessed with that square jawline, those bright green eyes, a flop of dirty blonde hair and the kind of symmetrical smile that would seem suspect if it weren’t so darn charming, he’s a Disney prince before they all became the bad guys. And he’s got the kind of effortless, high-wattage charisma that ensures a career beyond soaps and procedurals, the typical resting ground for the laughably handsome. Powell has something, you believe, going on behind the eyes.

This is all to say that suspension of disbelief is a prerequisite going into “Hit Man,” a decently entertaining action-comedy-romance about a fake hit man from filmmaker Richard Linklater, who co-wrote the script with Powell. It has made a brief stop in theaters before hitting Netflix on Friday.

Based on a “somewhat true story” though it may be, this is a film that asks its audience to buy into the idea that the characters in this film believe that Powell’s face is bland and forgettable. This has everything to do with his character, Gary Johnson, a philosophy professor in New Orleans who lives a quiet, solitary life in the suburbs tending to his two cats, birding, tinkering with electronics and helping the local police install surveillance equipment for sting operations. He drives a Honda Civic and wears ill-fitting polo shirts, knee-length jean shorts and socks with his semi-orthopedic sandals. And, of course, like many hot guys in disguise before him, he’s got a pair of wire-rimmed glasses. Why he dresses like your middle-aged uncle in 1992 is anyone’s guess. Were he in Bushwick, it might not even look odd. But this is a movie and we know that Gary is predestined for a glow-up.

Not that “Hit Man” allows itself to have any fun with the makeover aspect. No, once plain Gary is thrown into this amateur undercover work (by Retta and Sanjay Rao), we only get to see the final looks he wears to meet all the people looking to hire a hit man. He dips into the theatrical for these occasions, sporting wigs, makeup, accents and fake tattoos in his attempt to be what he thinks each specific person thinks a hit man should be, which is moderately amusing.

But besides a brief bit showing him watching a wig-and-makeup YouTube tutorial, his transformations are not exactly investigated. There’s no shopping montage, no Harvey Fierstein-type character helping him find his way around the college theater department’s costume room, and no apparent budgetary concerns or discussions, which seems odd for a guy who is only doing this undercover stuff for an extra paycheck. In a movie that perhaps had a better engine behind it, questions like these might evaporate with the laughter and enjoyment of a fairly silly premise. “Hit Man” does not quite have that, though. Again, that suspension of disbelief is necessary.

Things do pick up with the introduction of The Girl, Madison (Adria Arjona, terrific despite being awfully underdeveloped), an unhappy wife looking to get rid of her cruel husband. Gary meets her as “Ron,” who acts and dresses like the leading man of an action movie, or a cocky off-duty movie star, with well-fitting jeans and tight henleys and cool-guy jackets showing off his inexplicably ripped physique.

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And he treats Madison differently than the many other characters he’s helped put behind bars whose stupidity, trashiness and ugliness are all played for madcap comedic effect. She, he decides, doesn’t really want this — a grace he extends to no one else. He talks her out of hiring him to kill the bad husband, whom she promptly leaves without incident before moving into a nice house and beginning a steamy romance with Ron.

Again, questions arise about how this woman whose husband didn’t allow her to work and who was so scared of him that she was ready to hire a hit man has managed to escape so smoothly. But, you know, good for her and good for us because the chemistry between her and Powell is electric and ravenous, up there with George Clooney and Jennifer Lopez in “Out of Sight.”

But the honeymoon only lasts so long and things soon get tricky as Ron starts to become Gary’s dominant character. This all builds to a fairly exciting third act with the introduction of an actual murder and the possibility of being exposed by an increasingly suspicious and crooked cop (played with slimy perfection by Austin Amelio). And you can’t help shake the feeling that it needed something else: a bigger twist, a stickier conflict, some heightened stakes.

“Hit Man” was a movie that got some breathless praise out of the fall film festivals, which might be to its detriment. It’s perfectly enjoyable: a glossy, easy-to-digest Powell showcase that isn’t trying to be anything but fun. But the second coming of the action-comedy-romance, it is not.

“Hit Man,” a Netflix release, is rated R by the Motion Picture Association for “language throughout, sexual content and some violence.” Running time: 115 minutes. Two and a half stars out of four.