What do you leave out? That may be a question for Paula Vogel, the celebrated playwright whose new work opened in a world premiere at Wilma Theater on Wednesday.

It's a difficult question, especially after two years of research and collaboration with a theater company and its long-hired cast. If Vogel answers it, her sprawling, inventive "Don Juan Comes Home from Iraq" will fine-tune its focus – and its power will surge even more.

Vogel's play about a Marine platoon leader who's mentally broken after his mission in Iraq honors anti-war plays over the centuries – one of them is the 1936 play "Don Juan Comes Back from the War" by Austro-Hungarian Ödön von Horváth. While Vogel's play is not an example of what's called "devised theater" – theater artists come together and collectively create a play and its production – it has some of those elements: Blanka Zizka, Wilma's artistic director, was involved from the beginning in 2011, the cast was hired early on to work during the play's development, and the process included many interviews with soldiers returning or on leave from Afghanistan and Iraq.

It's been a major undertaking for Vogel (a Pulitzer winner for her perfectly written "How I Learned to Drive"), and for Zizka – she directs "Don Juan." The Wilma delivers a spectacular, intense production of a play set in two distinct and shifting places in the psyche of the lead character: reality and delusion. Part of Don Juan's problem is that he cannot tell one from the other. Part of the play's problem is, neither can we.

And so I found this story confusing, even as I was swept into its theatricality – in this case, a dark and convincing world set on Matt Sauders' pivoting stage that moves to different levels between and during scenes, and lit by Thom Weaver's haunting design.

"Don Juan" is essentially about a soldier (a sterling performance by Keith J. Conallen, who oozes with bafflement) desperate to reunite with his lover. If she's living – and she may be living only in Don Juan's mind – she's probably somewhere in Philadelphia, where he met her on a leave. Her name is Cressida (Kate Czajkowski, beguiling in her understatement), not the Cressida who was a hostage in the Trojan War, but a woman who feels like a hostage after she joins the reserves and, by unlikely coincidence, ends up deployed to Don Juan's command in Iraq. ("I am breathing their death inside me," she says desperately of the Iraqis caught up in the violence.)

Within that set-up, "Don Juan Comes Home from Iraq" takes on a flock of tough issues that become parts of Vogel's plot devices: U.S. involvement overseas; the inability of a military constructed for men to respect the abilities of women it seeks as soldiers; sexual abuse, from manhandling to rape by powerful superior officers (particularly timely now, given the news); the case that America discards addled soldiers once they've returned. The Marines' ideal, "simper fi" – always faithful? To whom and for what, the play demands. Just what defines leadership, it asks subtly -- then not so subtly: How does an increasingly clueless America process the idea of laying down lives, let alone war?

That's a lot to ask – and Vogel's mission here is noble and necessary, especially in the service of theater that's urgent, revealing and adventuresome. Still, "Don Juan Comes Home from Iraq" suffers from too much of too much. For a while during its intermissionless two hours, the issues were speaking to me more than the characters.

Just as she's esteemed as a writer, Vogel is revered as a teacher of playwriting – many stage works we see nowadays are by students who took off from under her wings. She is known in theater circles for her playwriting "bootcamps," as they're called, in which theater artists come together for a weekend immersion in writing and thinking about theater. I covered her bootcamp here as a journalist in 2011 – Vogel graciously encouraged me to participate so that I could get a first-hand feel for the work involved – and Zizka, the Wilma's leader, was part of it. The two artists clicked, and soon after, "Don Juan" became more than an idea.

The play, which Zizka directs with an impeccable feel for its dreaminess, has many elements of the main playwriting exercise that Vogel oversaw that weekend. She asked us to write a one-act, to choose a real place in Philadelphia as the setting, to incorporate at least one character from history or literature, or from something current. Vogel does all this in "Don Juan," whose geographical settings are Iraq and Philadelphia. In one particularly clever scene, Don Juan is confronted in Old City by a cocky Ben Franklin (Lindsay Smiling), who uses wit as his weapon and his cane as a backup. In another, the veteran holes up for the night (or thinks he does) at the now-ramshackle Divine Lorraine on Broad Street. His story is brashly serenaded in a Center City bar by a rollicking punk singer (Sara Gliko). He's as startled by the Mütter Museum as he is by his own locked-out sense of the city.

Others in the splendid cast of mostly Philadelphia-based actors take on multiple roles set here and in Iraq: Melanye Finister, Yvette Ganier, Hannah Gold, Brian Ratcliffe and Kevin Meehan. A few of the cast members, in their playbill bios, acknowledge the nation's troops and veterans. It struck me as remarkably fitting for this ambitious play, which does nothing to dishonor such service, and everything to question the way it functions as a part of the world's culture.


"Don Juan Comes Home from Iraq" runs through April 20 at the Wilma Theater, on Broad Street near Spruce. 215-546-7824 or www.wilmatheater.org.