Karen Hartman's Project Dawn, running through July 9 at People's Light in Malvern, is one of the very best productions of the season. It's a big moment as play and as theatrical entertainment. It's also important for how it got written, and the worthy — in fact, crucial — social work it does.

Our scene is the Project Dawn Court, a real "problem-solving" court in Philadelphia for women with multiple arrests on charges of sex trafficking. Hartman spent months visiting and researching the court, its founders, those served, and its impact. Some characters are composites of some of the best people in our city. In a brilliant stroke, Hartman's seven-woman cast alternate roles, now sex workers, now officers of the court. Judging and judged switch places, life for life, vulnerability for vulnerability.

To be part of Project Dawn Court, the women must plead no contest to their current charges. They then enter a program of supervision, treatment, drug testing, and rehab. If they fail, they can get up to the maximum prison time. If they "graduate" clean, charges are dismissed.

Hope and tension thus rule the courtroom (a clever set by Jessica Ford). Everyone — from Gwen (the brilliant Antoinette LaVecchia), lawyer and founder of the court, to Judge Kaplan (the fabulous Janis Dardaris) to tough Kyla, the D.A. (played with sensitivity and passion by Yvette Ganier) — is rooting for the women. But these are the abused and addicted: They lie, they whine, they wheedle, they try to play the system. Failure is ever potential. But the alternative? Arrest, conviction, release, and more abuse. So Gwen keeps advocating, and Kyla and Judge Kaplan stay hopeful.

The court is almost all volunteer. Gwen keeps begging for a full-time hire (she has two other lives, as lawyer and mom), but the Mayor's Office refuses. The work and pressure threaten Gwen's world.

Shondell is "graduating," and her graduation speaker is Bonnie, a Project Dawn alum. Dardaris doubles as Bonnie; judge becomes star graduate. Just as Bonnie has horror stories and advice — "Respect the demon," she says. "Don't be so strong that you're weak" — Judge Kaplan has her own demons. At a workshop on power issues in the court system, she runs from the room in tears.

The spectacular moments are many. Gwen, wineglass in hand, rants at her family at home: "Pizza's here. Wash your hands and say grace." Ganier is very fine as a butch D.A. who challenges Judge Kaplan on racial inequities and later violently advocates for Krystal, a delusional, homeless woman who needs psychoactive therapy. Shondell, at graduation, says she'll miss drugs: "There's no feeling on this Earth beats young and high."

But the peak is Sister Carol, nailed by superb Danielle Skraasted. As a bride of the Lord, she has no time for juridical niceties: "I'm on this side of the fence — I don't need to care about the process." She reminds us of the yawning gulf between what's moral and what's legal.

The play is not so much an arc as a slice of an endless struggle, a braid of stories. As written, it depends on women telling of their lives, and Hartman may wish to work on just how those backstories roll out. As directed (very well by People's Light artistic director and CEO Abigail Adams), there are a few too many hopeful looks and encouraging smiles in the courtroom (it could actually be a little tougher). And a couple of big moments are telegraphed.

But this fiery play comes with news of the law, the criminal system, the "life," women and men, and how things work or don't work in city government. Project Dawn is more adult and has fewer illusions, and yet believes harder, than the next play you're likely to see. It's yet another excellent product of the Rolling World Premiere Program at the National New Play Network, which has given us some precious gems lately (including The Arsonists at Azuka and How to Use a Knife at InterAct).

Theater is social work. That gets pooh-poohed or of-coursed to death. But as soon as a person stands before a group of others and speaks, a transaction begins. We may see our world mirrored, questioned, parodied, lambasted. You're going to see all that in Project Dawn — which is why you should go.

Project Dawn. Through July 9 at People's Light, 39 Conestoga Rd., Malvern. Tickets: $33-$87.34. Information: 610-644-3500, peopleslight.org.