In the first scene of Isaac Gomez’s harrowing drama “La Ruta,” receiving its world premiere at Steppenwolf’s Upstairs Theatre, a woman named Yoli (Sandra Delgado), discovers that her teenage daughter Brenda has disappeared.

She has company when she makes the discovery. Her friend Marisela (Charin Alvarez) waits at the bus stop too, handing out flyers seeking help finding her daughter, who went missing some time ago.

Set in the late 1990s and early 2000s, “La Ruta” depicts life In Ciudad Juarez, Mexico — just on the other side of the border from El Paso, Texas — where hundreds of women were kidnapped and/or killed over a period of years. In the play, the events have become so routine that, when Brenda does not show up on the last bus home from the maquiladora (factory) where she works, all it takes is a glance between the friends for Marisela to respond: “I know,” she says, “I’ll call the police.” In Alvarez’s expert hands, her voice already tells us that the police won’t help.

‘La Ruta’ ★★★ When: Through Jan. 27th Where: Steppenwolf Theatre, 1650 N. Halsted Tickets: $20 – $89 Info: steppenwolf.org Run time: 1 hour and 35 minutes, with no intermission

Gomez, a Chicago-based playwright rapidly gaining a national reputation, has written a genre-bending work with “La Ruta.” There’s an element of docu-drama — Rasean Davonte Johnson’s projections include dates appearing on the back wall of Regina Garcia’s spare but evocatively realistic set, telling us how long before or after Brenda’s disappearance each scene takes place.

As the scenes unfold in non-chronological order, Gomez also weaves something of a mystery whodunit, with suspicion falling on the fascinatingly contradictory character of Ivonne (Karen Rodriguez), who befriends the innocent Brenda (Cher Alvarez) at the sewing factory, and who, in Rodriguez’s superb portrayal, can switch from sweet to menacing in a moment.

There’s also a clear, social justice plea embedded throughout the play, with a guitarist (Laura Crotte) onstage and songs infused at various points, particularly when the atmospherics of laborious factory work or protest marches need emphasizing.

Ultimately, though, the play never becomes a full-blown mystery, nor does Gomez seem much interested in trying to detail events in journalistic terms or explain the murders by delving into causative social factors. NAFTA, worker exploitation, drug cartels, human traffickers, police and government corruption all get referred to, but not much more.

Where “La Ruta” excels, what makes it effective and affecting, is Gomez’s deeply sympathetic portrayal of Yoli and Marisela’s feelings of helplessness, anger, and constant battles against despair.

Under Sandra Marquez’s impressively specific direction, there really isn’t a false beat in a production filled with fraught, intensely emotional scenes. The all-women ensemble delivers a collection of extraordinary performances.

Delgado and Charin Alvarez, both veterans of Teatro Vista, detail a complex friendship that can barely stand the strain of the tragedy each character confronts. Although they share something so powerful in common, they’re also rarely in alignment in their processing of loss. In what is probably the best scene in the play, they face off, not quite accusing the other of being partly responsible for their child’s fate, but not quite avoiding that either. Their scenes fully expose their confusion, as they each admit to having to believe in something they know is unlikely, because the opposite is impossible to accept.

As Brenda, relative newcomer Cher Alvarez emanates teenage naivete, her character’s likability and cluelessness of her fate making even her lighter scenes feel painful.

Rodriguez has delivered a series of impeccable, primarily comic performances in the last year —including at Steppenwolf in “The Doppelganger” and in Gomez’s own thriller “The Displaced” at Haven Theatre. In “La Ruta,” she demonstrates skill on a different level, making Ivonne a layered figure who has so fully internalized the culture of Juarez that even she doesn’t know what she’s capable of doing. If anyone wants to know what living in constant fear can do to a person, this is a performance to behold.

Despite being set in the past, “La Ruta” has plenty of contemporary relevance. At a time when “caravans” of people trying to escape similar violence are being depicted by the U.S. president as dangerous rather than brave, Gomez’s humanization feels necessary.

Steven Oxman is a local freelance writer.