Director Alexander Payne says he doesn’t understand why audiences are calling his latest film, “The Holdovers,” a heartwarmer, but I sure felt warm and toasty leaving the theater, if a little tight chested.

The film centers on Paul Hunham, played by Paul Giamatti, an uptight, unliked classics teacher at a New England boarding prep school tasked with babysitting the boys left alone over winter break. By Christmas, the group has dwindled down to just three: problem student Angus (Dominic Sessa), abandoned by his honeymooning mother, head cook Mary (Da’Vine Joy Randolph), who has just lost her only son in Vietnam and Hunnham himself, who has no one in his personal life to begin with. As Christmas approaches, Hunham and Angus’s battle of wills threatens to boil over.

You can see the plot coming a mile away–of course the three form a bond and learn to understand one another. On paper, it’s a movie you’ve seen a million times, but the film is so candid that you feel you’re seeing something entirely new. Although it would be easy to settle into an idealized period setting, Payne does not shy away from the ugliness and inequality of the Vietnam War era. For every snowy tableau and Christmas party, there is a glandular disorder and dislocated shoulder to balance it out.

“It just went on and on” is usually reserved for films that drag themselves out longer than necessary; I consider going on and on one of “The Holdovers’” great strengths. It could have ended safely half a dozen times before it reached its culmination, but the film always pushes further than I thought it could. Payne works hard to earn your emotional response. It owes as much to its actors as its script: Giamatti and Sessa are a strong duo, even when they are at each other’s throats.

Shot digitally on location and edited in post for a 35-millimeter look, the film’s vintage feel increases its emotional charm. It doesn’t lean on its aesthetics, nor does it mimic a stereotype of the 70’s to make it easy for the audience. Instead the movie exists comfortably in its setting and lets you piece the period together on your own.

“The Holdovers” manages to be sensitive without being sappy, and bittersweet without succumbing to pessimism. It might not be the most blindingly jolly Christmas movie, but I can easily see “The Holdovers” becoming a fiercely human holiday classic.