It’s been a while since I saw a movie that was just plain fun from start to finish. Richard Linklater’s “Hit Man” fits the bill.

It starts with a voiceover from Gary Johnson (Glen Powell, the It Guy of the moment) explaining that there are no real hit men, no one you can hire to kill your spouse, your enemy, the person you believe harmed you so much that they deserve to be dead.

Johnson should know, because for several years, he was a pretend hit man for the New Orleans police department. His full-time job was teaching at a local university, but he also worked for the cops part time planting bugs and setting up wires while an actual undercover officer went in for a face-to-face with someone who hoped to hire a murderer. But when that cop gets suspended, Johnson is called upon to take his place and act like a hit man named Ron.

It turned out he had a real gift for the role and the movie shows him meeting some comically stupid people who end up arrested and (mostly) behind bars due to his ability to get them to say the magic words and cough up some money. Johnson wasn’t just good improvising as Ron, he really got into it, coming up with clever disguises, voices, and false teeth. The job also changed his real-world look, as he shed his professorial glasses, combed his hair differently, and had more swagger — to the point that one of his female students commented to a friend, “When did our professor start looking hot?”

One of the people Ron meets is Madison Masters (Adria Arjona), who wants to hire him to kill her husband. But Ron is taken with her and talks her out of the plan, suggesting that she just leave home and start a new life. Madison follows his advice and soon falls into a romantic relationship with Ron that feels at times as sexy as the scenes of Kathleen Turner and William Hurt in “Body Heat.”

In the hands of a lesser director, “Hit Man” could have been full of cliches and boring pacing. But with a master like Linklater at the helm, things move briskly, there isn’t a moment of downtime, and Powell (who co-wrote the script with Linklater) really shines. You can literally see him turning into a Movie Star. Powell clearly had as much fun playing Ron as Johnson did, and his co-star, Arjona, doesn’t miss a beat, either. Their timing of the witty verbal byplay, plus their clear physical attraction, had me thinking of classic film noirs (e.g. “Double Indemnity”).

That’s how good “Hit Man” is. I’m deducting a half point because the ending doesn’t quite tie everything up in a bow, but it still gets a 9.5 out of 10 from me, which makes it the highest-rated movie I’ve seen this year. Streaming now on Netflix.