Em Grosland, Amy Morton, Ty Olwin, and Francis Guinan Photo by Michael Brosilow

The curtain rises on a disaster of a living room, with clothes and boxes strewn all over the floor and the TV set blocking the front door. The father, Arnold (Francis Guinan), is wearing a woman's nightgown and wig, has his face made up, and speaks only in monosyllabic grunts. He seems to be in something just above a vegetative state. His caregiver—if you can call the treatment Baby Jane (as in Whatever Happened to Baby Jane) gave her sister Blanche caregiving—is his wife Paige (Amy Morton).

Returning home for the first time in three years after a stint in the Marines is son Isaac (Ty Olwin). Given the troubled relationships of this obviously dysfunctional family, the changes in the family dynamic are all news to him. He was unaware of the stroke that put his father in such an incapacitated state and is equally shocked to be told he now has a brother—his former sister. One by one, mother Paige explains the rules—and lack thereof. "We don't believe in order anymore," she says. They don't put things away, don't plan meals, don't budget. "Your father was the one who liked order," she tells him. Arnold is wearing makeup, a wig and a dress because he likes it, she insists. Besides, she's including estrogen in his meds to keep him docile.

Max enters from his bedroom, and in addition to reinforcing the rules about pronouns, shows himself to be assertive to Paige, taking full advantage of the new rule encouraging children to express themselves. Isaac, who has his own baggage involving the reasons he left the Marines after re-upping twice, begins to put things back in order while Paige and Max are away on their "cultural Saturday" outing of a trip to a museum. He puts himself in the position of the adult in the room—and after three years of picking up severed body parts and dead bodies in Afghanistan, feels well prepared and determined to clean up the mess that has become of his family's home.

The conflict that begins between Paige and Max reveals more layers to this play, written by performance artist Taylor Mac. Mac, who has written and performed extensively about gender identity and chooses to use "judy" as a possessive pronoun referring to judy's self, initially seems to be offering a satire, albeit a sympathetic one, on current attitudes toward gender identity. How many gender designations are there? At least 12 that Max and Paige can name and they abbreviate them all as LGBTTSQQIAAP. Or maybe there are none, as was considered the truth in earlier societies.

As we learn about the troubled marital history of Paige and Arnold prior to Arnold's stroke, we learn that Arnold had power over Paige coming from Arnold's status as the man in the relationship. Now that Paige is the one with power over the incapacitated Arnold, she is happy to assert it—in frequently cruel ways that go beyond keeping him docile and dressing him in women's clothing and makeup. Though Paige adorns Arnold as a woman, she doesn't seek to become a man in his place. Rather, she endorses the idea of a genderless world. So much that, while she supports Max's decision to reassign his gender, she begins to feel threatened when Max declares himself to be a masculine gay trans male.

Hir seems to question everything we may ever have believed or taken for granted about the concept of gender in mammals. In that, it's an usually thoughtful and provocative play and it's impeccably executed here. It's impossible to imagine an actress better suited for the role of the raging Paige than Amy Morton, who brings back memories of her fierce Barbara in August: Osage County and Martha in Who's Afraid of Virginia Woolf. Her fellow Steppenwolf ensemble member Francis Guinan bravely mumbles and drools as the near vegetative Arnold, even appearing onstage in nothing but a diaper at one point. Director Hallie Gordon has matched these Steppenwolf vets with the young Ty Olwin and Em Grosland. Olwin effectively seethes and then takes action as the responsible son Isaac, building up to a frightening and heartbreaking final confrontation with Morton's Paige.

And it's hard to imagine a more perfect Max than Em Grosland, who describes himself as a non-binary trans male actor. His is a brilliant performance, making Max a hopeful, energetic and optimistic teen who is somehow confidently finding himself amid the incredible chaos of his surroundings. It seems part of his positive attitude may be coming from never having known a normal family life. It may be that he simply takes all this in insanity around him as normal. Or maybe he's just so much happier in his true gender that everything else seems secondary. Whatever the circumstances, you do pull for him.

Hir is wickedly funny, but also a little hard to watch in places for Paige's cruelty to Arnold, even given the history between the husband and wife that may have led her to this point. Because that all happened before the action of the play begins, we have no natural sympathy with Paige. Instead, we're as shocked as Isaac is upon entering this home. It's hard not to feel pity for them all. And this is all set against a script that intends to entirely upend our constructs for viewing gender, an experience that is stressful enough to begin with. It's probably good, though, to experience Mac's play and start dealing with these questions. If the issues in the play are predictive of societal changes regarding gender over the coming years—and it seems likely they will be—the days when we were just wondering who should use what bathroom will soon seem quaint.