What is a song? What is an obstacle? What is a dream, and how does it die? Jez Butterworth’s play “The Hills of California” explores these questions through the story of the four Webb sisters. Their flaws and vulnerabilities give the play its power, even as the structure frays at the edges.

“The Hills of California” unfolds in a crumbling Blackpool guest house, whose decline mirrors that of the family within its walls. It’s an ambitious two-and-a-half-hour family drama that delivers sharp character work and striking set design but falters in pacing and payoff.

The production, which runs from Sept. 12 to Oct. 12 at the Huntington Theatre, toggles between two timelines. In the present, the Webb sisters reunite at their dying mother’s home; in the past, the four girls drill for a career as a family musical act. With content warnings for physical, verbal and sexual child abuse, the play confronts weighty themes of death, trauma and assault with mixed success.

The play opens as the youngest sister, Jillian (Karen Killeen), confers with Biddy (Patrice Jean-Baptiste), her mother’s nurse. Soon, sisters Ruby (Aimee Doherty) and Gloria (Amanda Kristin Nichols) arrive. Flashbacks introduce the family in their heyday: young sisters Joan (Kate Fitzgerald), Jillian (Nicole Mulready), Gloria (Meghan Carey) and Ruby (Chloé Kolbenheyer), along with their formidable mother, Veronica (Allison Jean White) and pianist Joe Fogg (Mike Masters). In these scenes, the family’s founding myth takes shape: four girls, driven by their mother toward professional success, beset by bad luck and missed opportunities.

As the timelines trade off, Jillian, Ruby and Gloria wait for Joan, whose travel from California has been delayed, for their first reunion in two decades. Each return to the past and each flare of present-day tension darkens the portrait, especially around Joan. By the final act, the cause of the sisters’ long rupture is revealed, and Joan’s belated arrival offers the four a narrow, fragile chance to make amends.

The best and most consistent features of “The Hills of California” are the sisters themselves. Their acerbic banter and fraught interactions convincingly trace the family’s division and loss; they come across as flawed, messy people pushed past the edge of control. I found the actors’ raw and compelling performances to be the strongest element of the production, and fortunately, the most important one.

Another standout is the set, which is among the most impressive I’ve seen. Veronica’s Seaview Guest House (which pointedly lacks any sightlines to the sea) is realized as an ingenious two-story revolving unit that spins from a public parlor on one side to a modest kitchen on the other. Although the action takes place in only two rooms, the production feels expansive rather than confined.

Other elements of the production are less effective, though intermittently powerful. The time shifts provide backstory without clunky exposition, while motifs and recurring images like small gifts and a broken jukebox are subtle and evocative.

Too often, though, disorienting choices distract from the show’s accomplishments. Minor irritants include unresolved storylines, a strangely positive presentation of smoking and unconvincing British accents. I was more put off by the play’s use of humor. Sometimes, the jokes humanize the Webb sisters as they cope with grief, but other times, the comic relief weakens scenes of family rupture and abuse. Quips traded among the characters resonate as painfully honest; gags pitched to the audience read as though the production doubts our ability to handle discomfort.

Another problem is the show’s erratic pacing. Some scenes drag while others feel too short. The opening hour introduces several unnecessary characters and plot elements; it feels like it could be cut in half without loss. And while the delay in Joan’s arrival is thematically relevant, it leaves too little time for all four adult Webb sisters to share the stage.

That compression drives my final criticism: the rushed resolution. The final stretch promises to unpack competing accounts of the past, probe the sisters’ conflict and offer a satisfying reconciliation. Instead, the mending of the family dynamic feels artificial and, for the first time, pushes the sisters out of character. Gloria, portrayed with edge and irritability for most of the play, softens toward Joan at a speed that doesn’t square with her twenty years of envy and resentment. A late twist suggesting that Joan has suddenly healed from childhood trauma lands as forced and inexplicable, delivering confusion rather than catharsis. Yet even here, you catch glimpses of the play’s potential. The final scenes contain some of the sharpest writing and most arresting moments: the silhouette of a masterpiece a few rewrites away.

“The Hills of California” is worth seeing if you have the patience for a spectacular set and meticulous character development with some detours and distractions along the way. Although its hurried conclusion, shaky pacing and awkward interjections blunt its impact, the play has a deeply moving and thought-provoking core that renders grief and resentment with subtlety and compassion.