“Flight Risk” sounds like the setup for a joke: What do you get when you put a U.S. Marshal, a fugitive and an unhinged pilot in a small plane? Get out your barf bag.

Mark Wahlberg, Michelle Dockery and Topher Grace star in this forgettable thriller- comedy that earns its debut in January among similar cinematic dreck. You’ve heard of slow- motion car crashes? Just substitute a plane.

In a sort of Dollar Store “Con Air,” Dockery plays a federal agent transporting Grace’s fugitive-turned- witness to testify against the mob. They need to get to Anchorage quick and enlist the help of a pilot: Wahlberg. Of course, not everyone is as they seem. OK, it’s Wahlberg. He’s a nut job.

Each member of this unholy trio seems to be in a different movie. Dockery is trying to be all Lara Croft, intensely problem-solving under immense pressure, very serious. But Grace is in a sitcom, trying out one-liners as the sarcastic nerd in the back of the plane. And Wahlberg has gone full sneering Hannibal Lecter, constantly threatening sexual violence.

That means that everyone in the movie isn’t flying in the same direction and the tone is all over the place. Brutal shootings and cuffed beatdowns mix with terrible puns and jokes at the expense of Spirit Airlines.

Wahlberg is the most fascinating misfire. His character is listening to the New Order song “Blue Monday” when we meet him; the fact that this sleazebag sociopath is enjoying a British New Wave classic wasn’t expected. Later, we learn that he’s wearing a wig. What the filmmakers are saying here is unclear.

Screenwriter Jared Rosenberg has an obsession with scatological humor, using multiple public urination moments and setting up one scene in which one of our heroes refers to having a “Museum of Modern Art in my pants” after a harrowing flying sequence.

Rosenberg has created an interesting scenario on board: killing the murderous pilot would seem to kill them all. But all we get is flabby dialogue. “You know the last thing that goes through your mind in a crash? Your ass,” says Wahlberg at one point.

In a desperate attempt to keep our attention, Dockery’s marshal during the movie’s latter third uncovers a conspiracy at the very top of the government using just her cellphone and natural suspicion — while at the controls of a small plane she cannot fly, 3,000 feet over icy Alaska.

She also, bizarrely, starts a flirtatious relationship over the radio with a pilot who is asked to bring them down safely — a meet-cute while, again, trying to steer a small plane she cannot fly.

The movie is an attempt to continue the cinematic rehabilitation of director Mel Gibson, and his return to the director’s chair after nearly a decade is passable. His camera is lively, shifting between the claustrophobic interior and the expansive Alaska snow-capped vista outside. Sometimes the camera is just too close, especially on Dockery’s mounting bruises.

But no one emerges unscathed from this funny-when-it-shouldn’t-be mess. The movie’s slogan is the weird “Y’all Need a Pilot?” but it should be “Y’all Need a Filmmaker?”

MPA rating: R (for violence and language)

Running time: 1:31

How to watch: In theaters