A middle-aged woman (Christina Kirk) joins four more senior women at a California pain clinic offering alternative, fasting-based treatments for a variety of serious ailments. They meet, sometimes all together and sometimes in smaller groupings, in chaises longues on a patio fenced off from a strip mall by a cement-block wall (designed by dots). Like the women of The Canterbury Tales, the characters in Annie Baker’s Infinite Life are pilgrims on a journey to wellness, an escape from a variety of modern plagues, who pour their faith into a regime of denial as well as companionship.

Like many of Baker’s plays, Infinite Life (which opened Tuesday at Off Broadway’s Atlantic Theater Company) does not provide an action-packed journey, nor much in the way of plot. Under James Macdonald’s languid direction, the trip is a long and meandering one, clocking in just under two hours, marked by long pauses and deliberate silences where character reactions matter more than any story developments.

These stylistic choices might succeed if Baker had a sharper point to make here, and if entire nighttime-set scenes were not played in near-total darkness — surely a real-world clinic would have a security light placed just above the patio exit door to at least partially illuminate the space (the frustrating lighting design is by Isabella Byrd). Worse, key speeches, particularly a crucial one toward the end delivered by the incomparable Marylouise Burke, are delivered so casually, so sotto voce, as to be almost incomprehensible.

It’s a shame because Baker’s characters are an appealing mix, from no-nonsense Elaine (Brenda Pressley) to the long, long-suffering Yvette (Mia Katigbak) to the sharp-tongued Ginnie (a scene-stealing Kristine Nielsen). Together with Burke’s Eileen and Kirk’s newcomer Sofi, they form a support-group sorority with a surprising dearth of rough edges. Despite all the fasting, in fact, there’s shockingly little conflict among the women, even on the surface. What we get instead is an artfully casual, hyper-naturalistic introduction to these women and their varied backstories, often in graphic detail — the medically squeamish should be forewarned. And the promise that any epiphanies will come, as they do in life, in moments so casual that you might just miss them if you’re not paying attention. The performances are understated but hauntingly real.

The most dramatic moment comes at the mid point, in a scene straight out of William Inge’s Picnic: A shirtless silver fox (Pete Simpson) arrives at the clinic — and quickly emerges as a kind of test for Sofi, whom we’ve seen leaving voice messages to her not-so-supportive partner back home and clearly struggling to find pleasure in her body amid all the pain it radiates. The new arrival, Nelson, has one up on the guy back home just for recognizing the validity of her condition — and his presence, and hunkiness, awaken a new sense of possibility in her. Must her body always betray her? Is the only path forward through denial, of sexual gratification as well as of food?

Baker doesn’t answer these questions, nor should she have to. But abnegation is seldom a path to compelling drama, and the issues raised in Infinite Life seldom probe very far beneath the surface level. To grapple with pain, and its origins, you sometimes need to cut much, much deeper.