The Reservoir ★★★★

Apropos of their name, Jake Brasch is an excitingly brash new voice in American theatre. At the most recent Edinburgh Fringe Festival, Brasch and Nadja Leonhard-Hooper made a buzzy splash with HOLE!, an absurdist, post-apocalyptic musical about a Christian sect leader in Nebraska who instructs his followers to wear butt plugs to survive “The Great Sucking,” a rapture-like event that actually comes to pass. What surprised festivalgoers in Scotland was that the show proved far more than a one-joke wonder; HOLE! not only explores the deleterious spread of cult-like thinking in America, it does so with believable characters and a wide-open heart.

Now New Yorkers can see what the fuss is all about as Brasch — flying solo — makes their Off-Broadway debut at Atlantic Theatre Company with The Reservoir, a touching and hilarious play about a young alcoholic’s messy attempts to get sober and the grandparents who do their best to help him.

Josh (Noah Galvin, delightfully impish) is passed out on stage from the moment the house opens and, for at least twenty minutes, doesn’t stir until the show officially begins, when he startles himself awake and addresses the audience: “The beach. Sunrise. Magenta. Lavender. Fuchsia. Wait a minute, I just realized something major: Sunrises are gay. This is the perfect way to wake up from a bender.”

Except that things are far from perfect. On medical leave from college because his drinking is out of control, Josh isn’t in Florida as he thought (he’s a hop, skip, and plane ride away in Colorado), and he’s got a nasty cut on his arm that needs both medical attention and an explanation. Josh isn’t an unreliable narrator; he just can’t remember much of his recent past, and concentrating requires more effort than he can muster. Assigned to shelve books at the store where his mom has worked for decades, Josh improvises: “Alphabetizing proved to be too hard, so I’ve kinda just been shelving by smell.”

Rather than turning inward as he tries to regain his sobriety, Josh decides to share his recovery journey with his four grandparents, believing that by so doing he will be helping them as well, particularly the two who are already experiencing different stages of Alzheimer’s. After doing some haphazard research on cognitive reserve theory, Josh believes he’s found the solution to both his memory loss and the brain blockages his grandparents are experiencing: “We all need pathways, new places for the water to go. Reservoirs. We each just need a reservoir!”

And oh, the places they will go, emotionally and neurologically.

One of the great joys of The Reservoir is the opportunity to see the different multi-generational relationships Josh has with each of his grandparents, who, once onstage, rarely leave it. And how fortunate Brasch and director Shelley Butler are to have this killer quartet of stage veterans as the grandparents: Caroline Aaron, Peter Maloney, Mary Beth Peil, and Chip Zien. Each beautifully captures the individuated love they have for their troubled grandson, even when they are frustrated or disappointed in him. Aaron has the richest of the four roles, and she seizes it with brilliant fierceness; her scenes with Galvin at the end of both acts are heartrending.

Where The Reservoir could use some filling is in the depiction of Josh’s internal journey. By focusing on Josh’s external search for a happier, more productive existence and not digging deeper into what has actually driven him to drink — we’re told little about his college life, almost nothing about his relationship with his father, and nary a word about his romantic life, or lack thereof — the audience is left to fill in one gap too many as he crawls his way through recovery.

Fortunately, that crawl is mighty entertaining. Butler does a great job keeping the action fluid and unpredictable, moving actors and props efficiently in and out of Takeshi Kata’s flowy, watery blue set, and Heidi Armbruster and Matthew Salvidar do excellent work playing all the other characters orbiting around Josh. The Reservoir is clearly an important and personal story for Brasch, and, given their distinctive voice, hopefully the first of many more to come.