Grieving doesn’t always travel a straight path; we rarely know how to negotiate the curves when they come. Manchester by the Sea is a film dominated by grief, and what writer-director Kenneth Lonergan makes clear throughout this deeply sad and prickly drama is that there is no roadmap for this process—not for the characters and certainly not for us in the audience. You’ll have to get used to its uncertain rhythms.

Casey Affleck plays Lee, a handyman with few friends living outside of Boston. Lee seems to hate his work and his ungrateful, nagging tenants, but he’s good enough at it. He’s the sort of guy you’d probably look right past unless you were at a bar where he drinks too much, ready to throw a punch at a gay couple who rub him the wrong way. Seems like a bit of a mess, this Lee. Probably best to steer clear.

One day, Lee gets a call that sends him back to his hometown of Manchester-by-the-Sea. His older brother Joe (Kyle Chandler) has died of the heart condition that’s plagued him for years. Lee doesn’t want to visit Manchester—he fled the town a few years ago, for good reason—but he needs to check in on Joe’s teen son Patrick (Lucas Hedges). To Lee’s shock, he discovers he’s been named as Patrick’s legal guardian, a task he desperately doesn’t want.

Manchester by the Sea chronicles two tragedies—one in the present and one in the past—and the film makes clear how intertwined they are. Lee has to prepare Joe’s funeral arrangements and tie up his business concerns but he also has to decide if he and Patrick will live in Boston—something the teenager absolutely doesn’t want—or if he’ll find someone else to take over as guardian. At the same time, for Lee the return home has reopened a painful trauma that destroyed his old life and ruined the family that he had built with pretty, feisty Randi (Michelle Williams) and their three kids. It’s best for viewers to go in not knowing the details—we’ll learn soon enough what happened, and then it’ll take the rest of the movie to absorb what we’ve learned.

Manchester by the Sea is Lonergan’s third film, after You Can Count on Me (2000) and Margaret (2011), and again he dramatizes characters with festering psychic wounds. Lonergan’s protagonists often don’t have the tools to express the depth of their anguish. Manchester by the Sea isn’t just about coping but also about how others in his characters’ orbit determine if they can or can’t carry that weight. This includes the viewer, too—there is perhaps no current filmmaker whose movies are so intentionally a challenge to the limits of our empathy.

It’s not uncommon for dramas nowadays to be led by an unlikable protagonist—an ornery or despicable individual whose motivations are bad and whose behavior is worse. TV’s current golden age has been built on the backs of the difficult characters of The Sopranos, Mad Men and Breaking Bad, but even this sort of so-called unlikeability has a dark allure to it, attracting us by tapping into the shadow selves we’re afraid to show the world. Lonergan’s characters are a different kind of difficult: They are sullen, temperamental, and sometimes thoughtless in a way that intentionally makes them insufferable. Lonergan doesn’t cushion that blow or go out of his way to ingratiate the characters in other ways. Like many of Lonergan’s creations, Lee is going through something, and he doesn’t care what any of us think about his way of navigating that pain.

Manchester by the Sea is filled with tenderness, sorrow, and more than a little knotty humor, but Lonergan wants a defiant sense of irritability to permeate as well. In Margaret, a petulant, beleaguered mournfulness pushed Lonergan’s emotional experiment to its furthest extreme. But with Manchester, he finds a way to make his characters’ misplaced anguish deeply affecting.

It’s not just Lee who’s hurting—there’s also Patrick and Randi (who returns to Lee’s life in devastating fashion) as well as Joe’s ex-wife Elise (Gretchen Mol). They’re all grieving in their own ways and sometimes for different reasons. (Elise, for instance, mourns the family she demolished because of her addictive behavior.) Everywhere the sullen Lee goes, he finds people who are sorry—there are still enough people in his hometown who haven’t forgotten about his awful act from years ago—and what’s remarkable about Manchester is that Lonergan simply allows these open wounds posing as human beings to bump into one another, inflaming each other’s tender spots, often without realizing it. Randi wants Lee, whom she hasn’t seen in years, to have a cathartic, cleansing moment with her, but he can’t bring himself to do it. Patrick wants to power through his grief with sarcastic jokes, his burgeoning garage band and his two girlfriends, but the revelation that his father will need to stay in a freezer until the ground is warm enough for him to be buried suddenly brings about a panic attack at the most unexpected of times.

In movies about grief, we usually get some sort of emotional handrail, a character or a storyline that we can hold onto as we chart these terrible waters of suffering. Manchester leaves us with nothing because the characters themselves don’t have anything. Lee’s stormy interior, unleashed at the most inopportune moments, has no hope of subsiding. Nobody in this movie is ever going to be made whole and Lonergan insists we don’t judge them. Everyone has encountered people—friends, maybe family members—who are grieving something, and we can often get irritated with how they conduct themselves. When is he going to snap out of it? Why isn’t she telling me how she’s doing? Why’d he yell at me? I’m just trying to be helpful. Lonergan’s movie can be too finely sculpted in places—its messiness is occasionally more dramatically convenient than wholly organic—but his wealth of muted performances and his capacity for caring argue that we need to be patient with others, even when they’re not acting their best. Someday, this will be us, and we probably don’t want to find out how badly we’ll break, too.

Grade: B+

Grierson & Leitch write about the movies regularly for the New Republic and host a podcast on film. Follow them on Twitter @griersonleitch or visit their site griersonleitch.com.