NEW HAVEN — The Long Wharf Theatre production of Julia Cho’s “Office Hour,” directed by Lisa Peterson and running through Feb. 11, will haunt the mind long after the lights go up.

This play asks questions we don’t want to confront. Does a “school shooter” have a typical personality? If we think we have met that person, can we reach him or her in time to soothe his pain and re-direct his anger? And what if we are wrong altogether about the person we think we are helping — he is either beyond our help, or he doesn’t need us in the first place? Cho refuses to provide answers, and that’s precisely what makes “Office Hour” so compelling.

On the surface, the plot is simple. Three university creative writing teachers —adjuncts — meet to talk about English major Dennis (Daniel Chung). Dennis has taken courses with Genevieve (Kerry Warren) and David (Jeremy Kahn), and he is now in a course with Gina (Jackie Chung). Genevieve and David warn Gina that Dennis writes such violently, and often sexually, disturbing stories that students — mostly female students — dropped their classes in droves. Of course, as responsible teachers, they each tried to talk with him, they say, but perhaps Gina would have more success since. . . well. . . she and Dennis have “similar backgrounds.” Gina, like Dennis, is Asian.

Galled by their racist assumptions, but determined to succeed where they have failed, Gina requires Dennis to meet with her in her office, where she tries valiantly to draw him out. The 85-minute production takes place here, as Gina flails in her good intentions and Dennis remains sullenly silent — until he doesn’t.

Cho uses overtly theatrical techniques to play out Gina’s and Dennis’s fears and anguish. Expect to be startled and disturbed by the unfolding action. Too, occasionally Gina acts in ways that beggar belief. However, director Lisa Peterson never allows us to lose sight of the script’s central compassion and ambiguity.

Intrinsic to the production’s success is Peterson’s superb casting and Maggie Morgan’s evocative costumes. Jeremy Kahn, as the angry and bitter David, deftly portrays a grown-up bully whose rage is motivated by fear. Arrogant and self-righteous, Kahn’s David is clearly blind to his own verbal violence. And his costume — a plaid jacket layered over a hoodie and a T-shirt, with a beanie on his head and a bag slung over his shoulder — suggests an aggrieved youth, as opposed to a concerned educator.

As Genevieve, Kerry Warren captures self-righteousness in another key: certain that she has done her very best with Dennis, she makes him Gina’s problem, thus coolly dismissing the depth and scope of her own accusations. And Warren’s costume, too, defines Genevieve’s hypocrisy: perfectly made up, and dressed in fashionable, opulent layers with large, eye-catching jewelry, she looks and seems more like an imperious, wealthy student than like the worried adjunct she claims to be.

Jackie Chung’s Gina stands as a stark contrast to her colleagues. Slim, delicate, and dressed in the minimalist outfit one would expect from a penurious but professional adjunct — a purple tunic over cream trousers, with slip-on Vans and little make-up or jewelry — Chung conveys a woman who can be gentle and kind, and yet unexpectedly forceful. Much of the drama depends on Gina’s urgent attempts to find the key that will unlock Dennis’s humanity and trust: Chung’s Gina is by turns clever and bumbling, strong and unstable, and above all, both naively and hubristically determined that such a key exists.

Daniel Chung, as Dennis, matches Ms. Chung’s deft ability to shift from mood to mood, and he provides the heartbreaking center of this production. Dennis’s journey, from masked silence, to terrifying violence, to utter vulnerability, keeps us riveted and just where Cho wants us to be: by turns sympathetic, uncertain, wishing to hold this child, and desperate to run.

Matt Saunders’ set design is spare and terrifically clever, and Scott Zielinski’s lighting moves, as it should, between realism and dream-like shock. The original music and sound design by Robert Kaplowitz reinforces the production’s enigmatic ambience.

“Office Hour” is not easy to watch at times, but especially because of Daniel Chung and Jackie Chung, this moving and profound production is not to be missed. We are privileged to delve into these questions through drama, for the questions could not be more real.