Christopher Abbott stars as the title character in “James White.” (The Film Arcade)

Cynthia Nixon stars as James White’s mother in Josh Mond’s feature debut. (The Film Arcade)

“James White” opens on a tight close-up of the title character, a young man in the process of getting seriously wasted — higher than a kite and hitting rock bottom.

Who is this guy, and what does he think he’s doing? “James White,” an extraordinary writing and directing feature debut by Josh Mond, proceeds to answer those questions, following the film’s damaged, vulnerable, arrogant, deeply loving protagonist through a particularly fraught chapter of his young-adult life. It turns out that James has a fairly predictable, if not impeccable, reason for overindulging in a New York bar, in what turns out to be the middle of the day. He’s on his way to an emotional gathering, during which we meet his stalwart mother, Gail; learn more about their fractured family history; and glean why their relationship is so emotionally freighted.

In many ways, “James White” hews to a typical coming-of-age dramatic arc, thrusting its soft, somewhat callow hero into tests and quests that will temper his character in important and permanent ways. What makes this movie different is Mond’s uncompromising proximity to his subject, who can never be easily pinned down, literally or figuratively. With the help of heroic camera work by cinematographer Matyas Erdely, Mond homes in on James’s face with unyielding focus that somehow manages to be frank and sympathetic at the same time. That commitment comes into even more powerful play in the film’s final third, when James faces a particularly life-changing challenge and emerges battered, bruised and incalculably the better for it.

It bears noting that “James White” is a grim journey, reminiscent of the 2012 film “Amour” by Michael Haneke, who Mond has credited as an inspiration. But it’s also exhilarating, thanks to the two performances that give it tenderness and toughness and truth. Christopher Abbott — until now, maybe best known for his brief appearance as a too-nice boyfriend on the HBO show “Girls” — delivers a revelatory performance as a not-too-nice boy-man who constantly, strategically, gets in his own way (until he very tellingly doesn’t). Cynthia Nixon, as Gail, goes from flinty to manipulative to protective in dizzyingly short order. When illness intervenes to irrevocably change their dynamic, what began as a sharply observant mother-son chamber piece turns into something far more raw and memorable. “James White” gets up close and personal in often discomfiting ways, but it’s never exploitative or glib. It hits the highs, and the rock bottoms, and all the damnable stuff in between.

R. At ArcLight Bethesda. Contains drug use, some sexuality and nudity, and language. 85 minutes.