In Liliana Padilla’s play at New York Theater Workshop, college students find empowerment and life lessons in a DIY self-defense class.If an attacker grabs you by the wrist, dip your elbow, turn your hand palm-up, twist and use leverage against the person’s thumb to extract yourself. If the attacker is straddling you, buck your hips, grab an arm and flip the person over.Though North Gym Room 2, with its drab walls and paltry set of yoga mats, aerobic steppers and stability balls, doesn’t look like much, at least the self-defense moves being taught there are legit.Because in Liliana Padilla’s “How to Defend Yourself” (winner of the 2019 Yale Drama Series Prize), none of the undergrads in the class really know what to do. They are still reeling from a peer’s beating and rape by two frat guys.The play, directed by Padilla, Rachel Chavkin and Steph Paul, opens a few minutes before the first session of a DIY self-defense class presented by Brandi (Talia Ryder) and Kara (Sarah Marie Rodriguez), sorority sisters of the victim, who has been hospitalized since the attack.Diana (Gabriela Ortega) and Mojdeh (Ariana Mahallati) arrive first. Diana, who is loud, tough and gun-obsessed, hopes to unleash her inner Tyler Durden in a real-world fight club; her friend Mojdeh is more concerned with how they’ll get into Brandi and Kara’s sorority. And there’s also Mojdeh’s upcoming date with James Preston, an Adonis of the college’s senior class. Nikki (Amaya Braganza), formerly known as Nicollette (“It’s a new thing,” she says meekly), creeps in late, shyly sliding her body into the room. Brandi, a practitioner of various martial arts, leads the group, including Kara, and, later, two well-meaning frat boys, Andy (Sebastian Delascasas) and Eggo (Jayson Lee), who also participate in the consent exercises and counter drills.The shots and blocks traded in the class are always martial but not always physical; rifts within the group are exposed during disagreements about how and when to safely express one’s sexuality with a partner and how to act in situations where the rules of consent seem to be a bit hairier. Diana worries about how Mojdeh, so desperate to lose her virginity, will fare in her dating life. Eggo and Andy fumble through an uncomfortable conversation about what one of them witnessed on the night of the assault. Brandi and Kara cruelly blame each other for what happened.But as the play progresses, almost exclusively in these defense classes, it feels as if the playwright is struggling to figure out where, and with whom, she should set the play’s highest stakes. At first it seems as if “How to Defend Yourself” will focus on Diana and Mojdeh, that their evolving relationship to their own bodies in this class will illuminate their friendship with each other, and vice versa. Then it seems perhaps we’ll land with Brandi and explore the origins of her own trauma.Ortega, left, and Mahallati as friends whose motivations for joining the class go beyond learning self-defense.Sara Krulwich/The New York TimesFor as much as the play aims to engage the audience in a fly-on-the-wall view of a group of people — several of whom are meeting for the first time, developing and changing in relation to one another in this contained space — it still neglects to provide the necessary context to make the pre-existing relationships and the character arcs feel real. Likewise, there are occasional throwaway plot twists, like that worn-out trope of a surprise same-sex kiss between friends, that detract from the show’s more novel reflections.There’s Nikki’s newfound courageousness, sparked by a few defense drills. Andy’s abstract theories on sex and, later, his stunned realization that he looks like, the kind of predator his peers are learning to defend against. Group conversations about what sexual autonomy looks like if what a woman finds most pleasurable is relinquishing her control; what control looks like; to what extent many young women and men define their relationship to sex by their relationship to shame.Like the script, the direction occasionally taps into what makes these characters unique. A handful of perfectly timed, expertly revealing line reads can be heartbreaking, hilarious and vicious. “Can you lick my forearm?” Eggo asks during a consent exercise, with Lee, hilariously unpredictable, as the awkward sexual reject.Ryder has a tough task with Brandi, trying to convey the vulnerability behind the character’s bravado and stilted dialogue, but she can also be downright scary when Brandi’s edge comes out. When Diana quips, that it’s just a class, Brandi retorts, too sharply: “Does that make you feel safe?” Among the standouts are Ortega as the wild Diana; Braganza, shrinking and ducking out of sight as Nikki; and Rodriquez, whose Kara is volatile yet wounded. But too often their characters are forced to fade away from the main action.The show’s stylistic breaks from reality — brief interludes of choreographed fighting or dance, like one character’s beautifully articulated dance to Beyoncé’s “Formation” — also bring color and vitality to the play but could be woven through more consistently. (The exciting technicolor-style switches from sickly, stuttering fluorescents to raging club neons are by Stacey Derosier, and the bumping sound design, including a playlist of Rihanna and the Weeknd, by Mikhail Fiksel.)“How to Defend Yourself” rushes through a random patchwork ending that allows the production to show off some fancy stagecraft but doesn’t provide a satisfying narrative conclusion.Before their first class begins, Diana, in the midst of hyperbolic ramblings, says they’re in a “fiction of safety.” She could be talking about the United States, or the town they live in, or the college campus, or even North Gym Room 2, where they shadowbox hypothetical rapists and kidnappers. Either way, I’ve felt that “fiction of safety” too — sometimes when I elbowed and kneed mats in taekwondo, when I’ve aimed punches at my reflection in the boxing gym — that, despite my having a black belt and solid stable of jabs and crosses, there are still limits to the autonomy I have over my own body. So is safety really just a fiction?And if so, how do you defend against a lie?How to Defend YourselfThrough April 2 at the New York Theater Workshop, Manhattan; nytw.org. Running time: 1 hour 40 minutes. More