Lucas Hedges -- the Brooklyn-born, breakout actor of film’s “Manchester by the Sea” -- makes his stage debut this week in MCC’s “Yen,” playing a sensitive teen left to care for his feral younger brother in a squalid U.K. council flat.

Hench and Bobbie, the main characters in playwright Anna Jordan’s thoughtful drama, have been largely abandoned by their fragile mother, who is cavorting around town with a boyfriend. The boys eagerly anticipate her rare visits, even though Maggie (Ari Graynor) is a drunk who can’t manage her own diabetes, let alone provide them any clothing.

To occupy time, the duo watch porn and purge aggression with video games they play on a big screen TV that is the focal point of the set (and pretty much the only furnishing in the place). For company, they have an unseen, but often-heard dog, Taliban -- so-named, Bobbie explains, “’Cos he’s vicious and he’s brown.”

It is concern for the dog’s welfare that brings a knock one-day from fresh-faced neighbor Jennifer (Stefania LaVie Owen, of TV’s “The Carrie Diaries”), a young Welsh girl, who has been observing activity in the apartment from her own home across the way.

Her arrival forces Hench (Hedges) to test the limits of his ability to move beyond the confines of his four walls. Jennifer’s late father called her “Yen,” and the pet name sums up what she represents to the boy: longing, to escape from his dead-end life, and foreign currency, which would give him the means to do so. 

Hedges, 20, is the son of screenwriter and director Peter Hedges (“What’s Eating Gilbert Grape”). Nominated for his turn as a Massachusetts teenager whose father dies early in the film, he is the youngest of this year’s Oscar contenders, in a supporting actor field that includes veterans Jeff Bridges and Michael Shannon.

He’s excellent here as a boy who copes with life by being prickly and snappish, but who is essentially introspective and caring underneath.

Justice Smith (“The Get Down,” on Netflix) is in a constant state of motion as Bobbie, the younger of the brothers, who has an ADHD-like disorder that’s never specified. Smith is a gifted actor, who makes us believe his storms of devotion and resentment are coming from the gut.

Bobbie’s adoration for his older, broken family members makes the climax of the two-act play, which might seem vague in lesser hands, thoroughly believable.

Graynor’s Maggie shows her bottomless neediness, without turning us against her. Owen, whose Jennifer is the only truly nice person in the whole piece, stands up for herself and calls out the boys for their bad behavior as necessary. When she suffers, and she will, it seems both genuine and painful.

“Yen,” through Feb. 19 at the Lucille Lortel Theatre, 121 Christopher St. Tickets: $49-$99. Call 212-352-3101.

Follow Robert Kahn on Twitter@RobertKahn