Sarah Chapin, Matthew Keenan (center) and Bradley Foster Smith in “The Lonesome West” at the Keegan Theatre. (Cameron Whitman Photography/ )

Never underestimate the power of tonal contrast. Much of Martin McDonagh’s black comedy “The Lonesome West” depicts the simmering hostility between two Irish brothers: Coleman and Valene Connor have long indulged in outrages that include threats, blackmail, violent brawling, streams of profanity and the malicious mistreatment of potato chips. It’s misbehavior rendered amusingly in the Keegan Theatre’s lively staging of the play, which features Bradley Foster Smith and a fine Matthew J. Keenan as, respectively, Valene and Coleman.

Still, “Lonesome West” ultimately draws its power from an ostensibly calmer central sequence, in which the feuding siblings do not appear. In this scene, conjured with commendable understatement in director Mark A. Rhea’s production, a discouraged and doubting Catholic priest named Father Welsh (Chris Stezin) confronts his own failure to encourage good behavior in Leenane, the provincial community where the Connors live. Stezin’s quiet, focused delivery of a pivotal monologue makes this scene, set on a lakefront, an eye-of-the-storm moment with a significant dramatic payoff.

The lakefront sequence serves as an effective foil to the tale’s more antic episodes, which benefit particularly from Keenan’s glowering charisma and deft comic timing. There is more discernible artifice in Smith’s evocation of Valene, although the details of the characterization — dweeby, hangdog looks and mannerisms — seem right for the character. The interaction between the two performers can be quite funny, including during the varied, expressive, deliberately goofball fight sequences, choreographed by Casey Kaleba.

Further characterization and narrative momentum are supplied by the rundown-farmhouse set, which comes complete with ripped armchairs, stashed-away bottles of poteen (the local moonshine) and lots of additional clutter, such as the religious figurines that Valene collects. (Keenan designed the set.)

When they aren’t engaged in one-on-one altercation, the Connor brothers sometimes play host to visitors, including the oft-­traumatized-looking Father Welsh and a high-spirited local teenager and part-time poteen merchant named Girleen, played here by a dynamic Sarah Chapin. These visitors bring news of the doings in broader Leenane, where violent death is surprisingly frequent, and even the local under-12 girls’ soccer team seems to have a homicidal bent.

The “Lonesome West” story kicks off just after the funeral of Coleman and Valene’s father, who in life was frequently arrested for screaming at nuns. (This play is part of McDonagh’s “The Leenane Trilogy.”)

Audiences familiar with the shocker-packed writing of McDonagh (whose works also include “A Behanding in Spokane,” which Keegan Theatre produced in 2013) will not be surprised to learn that neither the Connor family circle nor the farmhouse furnishings will emerge from “Lonesome West” wholly unscathed.

The Lonesome West by Martin McDonagh. Directed by Mark A. Rhea; lighting design, Colin Dieck; costumes, Erin Nugent; sound, Tony Angelini; set dressing and properties, Carol H. Baker; hair and makeup design, Craig Miller; assistant director, Josh Sticklin. 2 hours 20 minutes. Tickets: $35-$45. Through Aug. 27 at the Andrew Keegan Theatre, 1742 Church St. NW, Washington, D.C. Call 202-265-3767 or visit keegantheatre.com.