“The Accidental Wolf” is a web series from 2017 that was originally produced in eleven smaller chapters, but they’ve been re-packaged as a four-part limited series that debuts tomorrow on Topic, a new streaming service from First Look Media.

It stars Kelli O’Hara as Katie, a bored, upper-class housewife whose phone rings late one night. She doesn’t recognize the number but answers it anyway. There’s a man’s voice at the other end asking for help, while what sound like gunshots and explosions boom in the background. As he says he needs help for his pregnant wife, Tala, it sounds like he’s murdered. Katie, aghast, tries to get more information, but the call gets cutoff as the violent sounds increase.

When Katie tells her husband, Brad, what she’s heard, he tells her it’s probably a phone scam, like the Nigerian prince stories. She gets the same response when she reports the call to the NYPD, who tell her they have no idea where it generated and, besides, they would have no jurisdiction.

But Katie won’t take no for an answer, and hires a private eye to investigate. He, too, tells her it’s probably a phone scam, but he digs up a phone number that might be a lead. Katie calls the number, of course, and the mystery deepens.

I was impressed by O’Hara’s performance. Though she’s done some supporting work on TV and movies, she’s best known from her work on Broadway, where she brought luminescence to her starring roles in revivals of “South Pacific,” “The King and I,” and “Kiss Me, Kate,” among others. Doing musicals like those usually requires performers to play big, with broad expressions and little nuance. But in “The Accidental Wolf,” O’Hara proves her chops by dialing back those stage instincts into a subtle, quiet characterization of a woman whose concern for someone she’s never met drives her to try to unravel the mystery.

Unfortunately, Arian Moayed’s script and direction are so ploddingly slow that I stopped caring about the plot halfway through the second episode. Other Broadway veterans, including Judith Ivey and Laurie Metcalf, do their best in smaller roles, but can’t save this ship from sinking under its own weight.

I give “The Accidental Wolf” a 2 out of 10.