Zara Okonkwo is the most structurally ambitious playwright I have encountered in three years of watching downtown writers try to solve the multigenerational family play. “Mouth of the River,” which gets its first industry reading at the Millhaven Workshop on September 8th, is a play that refuses to let its three timelines behave — and the refusal is the argument.

The premise reads simply: a Ghanaian-American family in the Bronx, tracking the same household across 1987, 2009, and now, navigating land, inheritance, and what gets passed down that no one agreed to pass. The structure refuses to be simple. Okonkwo has built a play in which the timelines do not alternate in any orderly fashion — they interrupt each other mid-sentence, mid-gesture, mid-grief. The effect is not chaos. The effect is a formal argument about how inheritance actually works: not in clean succession but as interference, static, overlap.

This puts her in direct conversation with Branden Jacobs-Jenkins — specifically “Appropriate,” which also deploys the domestic space as a site where family history refuses to stay organized into the past. But where Jacobs-Jenkins gives us the debris of history accumulating inside a house, Okonkwo does something more austere: she gives us three generations speaking simultaneously, and the question of which voice the present moment belongs to is never finally settled. That is not a story conceit. It is a structural one, and it holds.

The reading will be directed by Adaeze Obi — who staged the Millhaven’s production of “Collinsworth” two seasons ago, the one that ran four weeks and left a crater — and will feature Lorena Vásquez, Chukwudi Eze, and Miriam Lassiter, among others. Casting at the reading stage is always partial information, but Vásquez in particular has a quality of existing very precisely in space that suggests she is the right body for Okonkwo’s central figure: a woman who inhabits all three time periods without fully belonging to any of them.

Here is my honest limitation: “Mouth of the River” currently runs about two hours forty minutes, and I have read the script. The third-act convergence — when all three timelines finally arrive at the same moment — is doing genuine formal work, but it is doing too much of it at once. The play earns its ambition for two acts and then tries to cash every check simultaneously. Obi will either solve this in the room or she won’t, and that is precisely what a reading is for. If it stays where it is, the ending will swallow the very precision that makes the first two-thirds so good.

That said: Okonkwo is the real thing. She is not mimicking formal difficulty — she has found a formal problem she actually needed to solve and has built a structure to address it. The tradition she is working in has produced some of the most important American plays of the last thirty years, and “Mouth of the River,” if the third act gets trimmed into coherence, has a legitimate claim on that lineage.

The September 8th reading is invite-only, but the Millhaven typically opens development work to public preview within two weeks. Get there then. Okonkwo has written a structural argument about inheritance that sounds like nothing currently running downtown, and it would be a genuine waste to let that go unwitnessed at the stage when it can still be shaped.