Where would Irish drama be without exasperated sons at war with their stoic, uncommunicative fathers? It’s a good question, as intergenerational showdowns are pretty much the lifeblood of Irish theater.

For decades we’ve had gifted sons laying into their poor old fathers for their coldness; and in turn we’ve had countless remote fathers struggling -- and failing -- to find a way to talk directly to their strapping sons. It’s enough to make a grown man weep. After a hundred years of sorrow and brokenness in the Irish theater, you’d be hard pressed to find a happy ending anywhere.

In “After Luke” and “When I Was God”, now playing back to back at the Irish Repertory Theatre in New York, Cork-born playwright Conal Creedon comes as close as any contemporary Irish playwright to charting the heart of darkness at the center of Irish family life. 

Directed by talented Irish actor and director Tim Ruddy, the two new Irish plays about fathers and sons now playing at the Irish Rep are already huge critical hits, reminding us that all you need to make good theater is terrific actors and a good script.

“After Luke” is set in the already far off heyday of the Celtic Tiger economy, when everyone in the nation was slapping inflated prices on property they previously couldn’t shift.

A version of the prodigal son parable, “After Luke” begins when Maneen (played with impressive precision by Michael Mellamphy) returns home to Cork to convince his well-meaning elderly father Dadda (Colin Lane) to sell his little plot of land for a fast profit.

 Immediately objecting to this harebrained scheme is Son (played with heartrending conviction by Gary Gregg), who likes his little life working in their scrap heap, thank you very much, and who is already boiling over from years of unexpressed resentments in any case.

Having lost his wife to suicide, Dada has raised two high maintenance siblings who are “chalk and cheese,” so understandably he’s looking for a little peace in his old age. But instead -- you guessed it -- he gets intergenerational conflict.

“When two elephants go to war it’s the grass that gets trampled,” Dada says, shrugging off his competitive sons and accurately predicting the outcome. Dada has never played favorites, but his preference for Maneen keeps breaking through with near fatal consequences for all.

Ruddy directs with enormous confidence, and his three male actors deliver the kind of performances that turn a good play into a great one.

Mellamphy in particular is a gifted physical actor who inhabits his characters with such conviction that they leap to life in front of your eyes. Only a prodigiously skilled actor can switch between roles, generations and genders with this kind of facility, and half the fun of the play is watching this alchemy take shape.

As Son, Gregg is utterly convincing, to the point where you actually start hoping that he can be shielded from the manipulations of his far more worldly wise younger brother. Gregg has enormous sympathy and understanding for his shy and lonely character, and he brings unforgettable pathos to his role.

The second play in the Irish Rep’s Creedon night is “When I Was God”, a fable that explores the long shadow cast by a thankless father. Young Dinny (Mellamphy) wants to play soccer but Father (Gregg) won’t hear of it, insisting that his boy play hurling like a true Cork man.

What unfolds resembles a sort of speeded up Punch and Judy show with Dinny positioned as the helpless prize that’s being fought over, night after night, year after year.

But there’s a sort of inevitability to both of these plays, a sort of wind them up and let them at it quality, in both the treatment and the writing, that means they never quite take off.

We’ve been down this dads versus lads road in the Irish theater many times before, to the point where we can anticipate each conflict before its even begun, and Creedon is, it seems, for the most part content to outline the well known signposts rather than branch out in any new direction. The inability to even notice alternatives, never mind explore them, is all the more striking.

“After Luke” and “When I Was God” are now playing at the Irish Repertory Theatre, 132 West 22nd Street in New York. For tickets call 212-727-2737.