For the first time since 2016’s “Hacksaw Ridge,” Mel Gibson again dons his director’s hat with the new thriller “Flight Risk,” out in theaters Friday. An enjoyable if standard B movie that takes place almost entirely on a small plane, it stars Mark Wahlberg as a contract killer, Michelle Dockery as a federal marshal, and Topher Grace as an accountant coerced into being a government witness in an upcoming trial against a mob boss.

From this setup, and because the three roles essentially make up the entire cast, one gets a sense of the film’s unambitious plot and how its pleasures will be slight. Yet its modesty comes across refreshingly, especially when compared with some of the other films Mr. Gibson has directed, epics like “Braveheart,” “The Passion of the Christ,” and “Apocalypto.” 

Based on a screenplay by Jared Rosenberg that was featured on Hollywood’s 2020 “Black List” as an unproduced gem, “Flight Risk” contains bits of cleverness, potty humor, dramatic turns of event, crisply choreographed action, and even heartfelt moments, all of which combine to create a fun viewing experience.

In terms of humor, dramatic stakes, and production values, the B movie bona fides of “Flight Risk” are apparent from its opening sequence, which involves a nerdy guy (Mr. Grace as Winston) hiding out in a motel cabin in the middle of Alaska, a microwaved cup of Ramen noodles, and a moose. The plot gets going once Ms. Dockery’s no-nonsense Madolyn Harris shows up to arrest and chaperone Winston, but it’s only when the two of them take their seats in the airplane and Mr. Wahlberg’s Daryl is introduced as the pilot that the film really takes off. 

Daryl is to fly them to Anchorage, which is about an hour and a half away — also the runtime of the movie. This real-time aspect, along with the economy of its characters and the tight confines of the setting, creates a heightened atmosphere akin to what’s expected when seeing a play. 

Early on in the flight, Winston makes sarcastic comments about his shackled state and Daryl flirts with Madolyn in a rather arch Southern accent. An underlying tension, though, soon erupts into full-fledged mayhem when it’s disclosed that Daryl is actually a hitman hired to kill Winston before he testifies. Each character then attempts to get the upper hand, through violence, bribery, psychological tricks, or just smarts. 

Once Madolyn gains control of the situation, she must figure out how to operate the Cessna and, with the help of an instructor on the phone, the movie doubles as a lesson in how to fly a small plane. This piloting teacher is one of a few unseen characters, with actress Leah Remini voicing Madolyn’s boss. Through her interactions with Daryl, Madolyn figures out there’s an informant amongst the marshals, and the suspense inside the plane is ratcheted up by the drama occurring elsewhere. Some of this “offstage” business provides an opening through which backstories come to light, but it also causes the film’s middle section to lose drag a bit. 

With top billing, Mr. Wahlberg clearly relishes playing “the bad guy,” a character type the actor hasn’t portrayed in a long time. Sporting a disturbing bald pate, he dives with gusto into Daryl’s twisted perversion and psychopathic reasoning. Yet the real lead role is that of Madolyn, with the British Dockery (of “Downton Abbey” fame) acquitting herself handsomely as the capable, vulnerable but tough U.S. marshal. Mr. Grace is typecast as the verbose, sarcastic, uneasy Winston, yet the script does allow the still youthful actor to deepen the character as he earns Madolyn’s trust and they share third-act heart-to-hearts.

As the movie whizzes to its climax, improbabilities in the screenplay loom larger, though they never grow big enough to take the sturdy vehicle down. Mr. Gibson handles all of it — the action, plot holes, comedy, and sincere dialogue scenes — with his consummate skill, leading one to hope his new role as one of President Trump’s “special ambassadors” to Hollywood won’t keep him from directing again soon.