The box office never ceases to amaze me. One of the best films I’ve seen in some time has made less than $4 million—despite being headlined by an A-list star. Compare Greenberg with The Back-Up Plan, a Jennifer Lopez vehicle rated just 21% positive on Rotten Tomatoes, which made more than that its first day. It’s not as if Ben Stiller, who plays the title character in the Noah Baumbach film, isn’t a box-office draw. Most of his last 10 movies made over $100 million each domestically, with quite a few making close to or more than $200 million. Perhaps potential viewers are frightened off when they scan reviews—even positive ones—and see phrases like “character study” and “mental breakdown.” Yet Greenberg is actually a very funny film—even though it is something of a character study of a man who’s recently had a mental breakdown.

Roger Greenberg, trying to ignore his own case of arrested development, wouldn’t be terribly out of place in a Nick Hornby novel. Though he’s not as immediately winning as the hero of, say, High Fidelity. His seeming inability to grow up and embrace commitment haven’t just landed him in the doghouse, they’ve landed him in a mental institution. He checks out and flies from New York to Los Angeles to take a recuperative stay at his brother’s place, while Phillip and his wife and kids take a trip to Vietnam. It says something about how disconnected Greenberg is that Phillip doesn’t bother waiting around to see how his brother’s doing after the trauma. Instead, before departing he instructs his personal assistant Florence (Greta Gerwig) to tend to anything Greenberg needs. She certainly gets more than she bargained for.

She doesn’t realize it immediately—Greenberg’s first request is a grocery list consisting of just two things: ice cream sandwiches and whisky. But the mostly directionless 20-something and the completely directionless 40-year-old soon find themselves drawn to one another, though this isn’t a romantic comedy. As Florence, not much of a wit, points out, “Hurt people hurt people.” We’re on Florence’s side, of course, but not only because she’s not the tactless jerk in the relationship. The film opens as the credits play over Florence driving through L.A., the wind blowing through her hair, music streaming out of the radio. The actress playing her isn’t obviously beautiful, but there’s something beautiful and intimate about this moment, about the only one in the film in which Florence seems comfortable with herself. Maybe that has something to do with what Florence finds attractive about this 40-year-old without job or relationship. She doesn’t mind his lack of drive; in fact, she admires his ability to feel content doing absolutely nothing. He’s even given up the carpentry that paid the bills.

Greenberg really isn’t all that satisfied with his present, though, and that’s because he can’t help reflecting on his past in the city in which he came of age. Greenberg shows us what hipsters are like all grown up. Some, like Greenberg’s ex-girlfriend Beth (Jennifer Jason Leigh, the director’s wife and co-writer), have kept an element of cool while their lives followed a not entirely happy trajectory. Others, like Greenberg’s friend and ex-bandmate Ivan (Rhys Ifans), are struggling to keep a family together despite the difficulty of giving up the attractions of youth. Greenberg hasn’t come to L.A. to make peace with the past; he’s there to pick up what he abandoned, to get the girl and reunite the band. He can’t see that they’ve moved on, because he doesn’t care much about other people. Greenberg’s struggle isn’t so much with any voices in his head, but those outside it. He’s railing against society, a point driven subtly but hilariously home with his frequent letters of complaint to companies about their customer service. “Youth is wasted on the young,” Ivan muses. “I’d go further,” Greenberg replies. “Life is wasted on people.”

The indignities of modern life that Greenberg can’t bear are peculiarly American. And so is this thoughtful and hilarious film, though some might feel its arty moments and lack of action seem more European. Noah Baumbach tried channelling recently departed French filmmaker Eric Rohmer in his last movie, the humorless Margot at the Wedding, without success. The writer-director who made Kicking and Screaming and The Squid and the Whale is much more at home chronicling American angst.