“If you know the type … you know the individual,” says father figure Harold early in Lyle Kessler’s harrowing “Orphans.”

Indeed, many plays have been written in which the characters reach into the depths of painful childhood memories to discover the roots of an unhappily conflicted identity. These characters are more often made better, but sometimes they are destroyed by the experience.

Kessler’s 1983 play traverses familiar but still touching territory in its story of two brothers forced to encounter realities they have long been avoiding in their struggle to maintain an odd little life in a rundown Philadelphia home.

In the Mad Horse Theatre production, directed by Chris Horton, the unsettling drama unfolds in an almost excruciatingly intimate way within the confines of the company’s small performance space in South Portland. It makes for a tough, engrossing and ultimately rewarding night at the theater.

The story concerns Harold, played by Michael Kimball, an apparently affluent businessman who is kidnapped by the knife-wielding Treat. Treat wishes to criminally advance from the small-time robberies through which he has been supporting himself and his stay-at-home brother, Phillip. As it turns out, all three are orphans. But the smooth-talking (once the gag comes off) Harold, older and with a much more sophisticated world view, soon takes control of the household.

There is a certain strange dynamic to the relationships established in “Orphans.” The author has expressed a preference for parable and allegory over naturalism. Themes of justice, escape and “dispensation” enter from odd angles, roles reverse and opportunities open only to suddenly close. A few laughs also find their way in.

Kimball mixed the blarney with the more “well-intentioned” wisdom he imparts to the young brothers well. He takes charge while still slipping in hints of a vulnerability he’s overcome at a terrible cost. His scenes with Dylan Chestnutt, as the slow Phillip who has been overprotected by tough guy Treat, were particularly effective.

Somewhat reminiscent of a young Matthew Broderick, Chestnutt conveys his character’s “simple faith” and innocent nostalgia for long-gone parents convincingly. He imparts Phillip’s blossoming under Harold’s “encouragement” in a nicely nuanced way.

Nathan Speckman is a ball of destructive energy as his Treat flails (sometimes literally) at an unjust world, though his thievery is hardly to be admired. Harold’s view of him as a “dead-end kid” irks him because he knows it fits. His final scene was intensely moving at Friday’s opening.

Harold’s memory of escaped orphans “pressing their faces against the windows” of the world is one of many haunting images that this affecting play brings home.

Steve Feeney is a freelance writer who lives in Portland.