The Commuter’s opening montage is far more artful than one might ever expect from a mid-budget action thriller coming out in January, playing out Michael’s daily routine over and over again in a series of cross-cutting scenes. We see him drive to the station with his wife, banter with his son about the book of the month they’re reading together, and say hi to his fellow passengers on the train. The viewer can spot little differences each time (he’s in a rush one day, he’s bickering with his wife on another) while also buying into that comforting sense of sameness.

By the time Michael boards that train to go home, anxious and depressed about his lost job, the audience is already familiar with his entire life and understands how it will be thrown into chaos. Collet-Serra has also already laid the groundwork for Michael’s relationships with the other regulars on the Metro-North, which is going to matter. Because then a mysterious woman named Joanna (Vera Farmiga) sits across from Michael and makes an odd request: If he can find a specific passenger on the train who “doesn’t belong” and is carrying mysterious cargo, he’ll walk away with $100,000.

What will happen to this traveler who doesn’t belong? Michael doesn’t know. Who is this woman Joanna, who immediately disembarks after making her proposition? No idea. But Michael is an ex-cop with two mortgages and a kid to send to college; the idea of free money for a simple detective job is enough to get the ball rolling. And once Michael starts trying to suss out who this mysterious passenger could be, well, things get dangerous fast.

Much like with Collet-Serra and Neeson’s previous collaboration Non-Stop (which was set entirely on an airplane), there’s an Agatha Christie element to The Commuter’s plot. The film is light on action set pieces (at least, until the last 20 minutes, when things really go to hell) and heavy on tense, loaded conversations with passengers. Forget Murder on the Orient Express, this is Vague Mystery on the Hudson Line, with Michael playing the part of a sweaty Hercule Poirot who’s at the end of his rope. Michael knows his pals, the regular riders of the train, aren’t of interest to Joanna—she’s looking for someone who doesn’t belong. From there, it becomes a process of elimination.

It’s almost charming watching the film find various ways to use the limited confines of a suburban commuter train in service of a nervy action thriller. There’s a claustrophobic fistfight between carriages that’s all elbows and throat-grabs, and a clever use of a non-air-conditioned car that’s empty and thus free for Michael to conduct more intense interrogations. There are altercations with the typically annoying sorts of passengers—the stockbroker yelling on his Bluetooth headset, the guy playing his iPhone game too loud—but does their behavior make them worthy of the nefarious fate Joanna intends for her target?