Acting, they say, is reacting, and the reacting is out of this world in “Skeleton Crew” at Yellow Tree Theatre.

Under Austene Van’s sensitive direction, the four-person ensemble is dialed in from the start of Dominique Morisseau’s drama, demonstrating the theatrical magic that happens when folks respond to one another with commitment and truth.

Jamecia Bennett’s Faye is the mother figure for a created “family,” always trying to make things right for co-workers at a failing Detroit factory in 2008: Sunny Dez (Mikell Sapp) is saving to open his own business. Shanita (Nadège Matteis) is a soon-to-be single mother. Reggie (Darius Dotch) is a supervisor torn between his regard for the other three and his bosses, who may be planning to close down the factory.

The showiest role is Bennett’s, and she is extraordinary, gradually building from worry to fear to a howl of rage and pain, but the key to “Skeleton Crew” is how expertly Van and the cast achieve a delicate balance. Morisseau has built the play in a classical style — each character has a secret and, ultimately, we’ll learn most of them — and our involvement depends on the tension achieved between Matteis’ effervescence, Sapp’s weighted-down optimism, Bennett’s mounting dread and Dotch’s trying-to-make-the-best-of-it sorrow. Morisseau, whose “Pipeline” appeared at Penumbra last year and whose “Ain’t Too Proud — The Life and Times of the Temptations” is now on Broadway, has created four terrific roles in “Skeleton Crew” and these actors make the most of them.

“Skeleton Crew” presents difficult problems — it’s about a vanishing way of life — and implies that the answers lie in the way we treat one another. “Nobody wants to merge no more,” Shanita complains after a difficult drive to work. “[Jerks] won’t let you in.” And Reggie wonders what happened to compassion, “whatever you call it that makes you stop seeing yourself in somebody else.”

Those are two tiny moments in a play whose characters all long for an ill-defined time when people cared for one another (there’s a sense that Faye is trying valiantly to recreate that time, writ small, in Nicole DelPizzo’s shabby-but-homey breakroom set). When economic and social pressures tear us apart, Morisseau argues, that’s when we must pull closer.

Morisseau’s second act isn’t as strong as the first, with naturalistic, often hilarious, dialogue turning speechy. And I see what she’s going for with interstitial scenes in which the actors appear in neon-lit cages, miming the dehumanized motions of an assembly line. But those scenes don’t jibe with her message that factory work is honest work, and the lighting makes the actors resemble “Solid Gold” dancers.

Still, her hopeful message comes through loud and clear, all the way to the last line of the play, a co-production with New Dawn Theatre: “The only way through it is to work together.”