“This Is Us” routinely brings viewers to tears. Next week, it’s taking them to the theatre. The hit NBC series will air an episode modelled on a one-act play and confined almost entirely to a hospital waiting room and to a single day, a sharp detour from its usual flashback storytelling.

In Tuesday’s episode (9pm EDT), the extended — and stretched to the breaking point — Pearson family is gathered after Kate Pearson (Chrissy Metz) goes into early labour.The setting is simple. The drama is anything but.

Brothers, spouses and partners clash as their anxiety unleashes anger and hurt over Kevin’s (Justin Hartley) alcoholism and Randall and Beth’s (Sterling K. Brown, Susan Kelechi Watson) marital strain.

As the hours tick by without word about Kate or the baby’s fate, there’s a frustrated — deeply warranted — outburst from her mom, Rebecca (Mandy Moore), and a milder one from Rebecca’s ever-patient husband, Miguel (Jon Huertas).

Even Kate’s peppy, well-meaning pal Madison (Caitlin Thompson) comes in for a rebuke from a hungover Kevin, while his wary girlfriend, Zoe (Melanie Liburd), weighs their future.

“This Is Us “ is known for its ability to make viewers cry, which explains the decorative tissue boxes gifted to series creator Dan Fogelman and scattered around his office. But “The Waiting Room” episode is both tougher than usual and a bold departure.Fogelman, also among the series’ executive producers, recalled the guidance he gave the episode’s author, playwright Bekah Brunstetter, when she started on the script.

“’I want to put a really intense, one-act play on national television, but I think the characters and the actors and the audience’s knowledge of them will make it accessible because everybody will be on board with them,’” he told her.

The result is a showcase for its cast, honored as best drama ensemble by the Screen Actors Guild in January against stiff competition that included FX’s “The Americans” and Hulu’s “The Handmaid’s Tale.” It also boasts Emmy winners, Brown among them. “You underestimate these actors as ‘television network actors’ at your own peril,” Fogelman said. “They’re doing some heavyweight stage work... I think they’re going to hold the screen for a network audience in a strange form that that audience is not used to.”

The episode evokes an earlier one in which Kevin enters rehab and, with the family gathered to support him, an 11-minute sequence shot in a single take plays out. But the drama has challenged convention from the start, with its intricate, era-jumping approach to Rebecca and Jack’s (Milo Ventimiglia) lives and those of siblings Randall, Kate and Kevin, nicknamed “The Big Three.”.

Associated Press