I’m sure Irish families are no more dysfunctional than others, but a pair of domestic tragedies that opened locally last weekend, in coincidental tandem, might send the message that they are. Both Eugene O’Neill’s towering classic Long Day’s Journey into Night and Deirdre Kinahan’s recent Dublin and London hit, Moment, examine, in the crucible of a single day, how the past contaminates the present and how deceptions, self-deceptions and simmering discontents spin their respective family circles into chaos.

Danny Eaton’s mission at West Springfield’s Majestic Theater is to entertain, amuse and occasionally challenge his largely middle-of-the-road audience. This season’s challenge is O’Neill’s masterpiece, an excruciatingly sad drama with a three-hour playing time (through April 1, majestictheater.com, 413-747-7797).

The play, a thinly veneered portrait of the playwright’s own Irish-American family, follows one day’s journey from denial of the troubled past and tortured present to bitter acceptance and despair. Hardly easy going, but last weekend’s audience was not only engaged but mesmerized, thanks to Rand Foerster’s sure-handed direction, the playwright’s poetically charged language, and a quartet of thrilling performances.

I missed the grand manner and “the great voice,” as one of the family taunts, in Kenneth Tigar’s early scenes as James Tyrone, a former matinee idol who squandered his talent in popular melodrama. But Tigar comes into his own in a long, wrenching, tortuous, brilliant drinking scene with Dan Whelton as O’Neill’s alter ego, the sensitive, tubercular younger son. As Jamie, the suicidally alcoholic elder son, drowning his regrets in cynicism and whiskey, Chris Shanahan gives the performance of his life.

The evening’s greatest gift is Beth Dixon as Mary Tyrone, a soul lost in memories, regrets and a morphine haze. Dixon’s performance, exquisitely detailed, unerringly focused and ultimately heartbreaking, is a master class in the power of performance. In a servant cameo, Kait Rankins more than holds her own in lofty company.

Moment is a kitchen-sink drama—literally. A counter and sink bisect the stage in Smith College’s studio theater, where the play, set in a Dublin neighborhood, runs through this weekend (smith.edu/smitharts, 413-585-2787). The title refers to a single irretrievable moment in the past, when teenage Niall committed an impulsive murder, and the play digs into its reverberations in the present. Niall has emerged from prison and built a successful career as an artist, but back home the crime still clutches at the women of the family.

Dubbed “car-crash theater” by a British critic, the play investigates the multiple collisions between the characters’ regrets, recriminations and uneasy attempts at reconciliation: a mother in denial, one sister in undiminished rage, the other trying to move on, with their brother attempting an edgy truce as their respective partners look on helplessly.

Ellen Kaplan’s production pulls a lot of emotion from her young cast—as well as pulling an unexplained gender switch in the script, boyfriend to girlfriend. The play takes a while to get going, but once the sparks start flying the piece gains momentum and power, despite a tendency to melodrama, some one-note performances—among some affectingly strong ones—and a jumble of faux-Irish accents.

Chris Rohmann can be reached at StageStruck@crocker.com.