This is not your momma’s Harper Lee.

Aaron Sorkin has famously re-worked “To Kill a Mockingbird,” drawing on minute parts of the original novel and reimagined a world where Calpurnia (LaTanya Richardson) speaks up to Atticus Finch (Jeff Daniels). And Atticus, who used to take Bob Ewell’s spit and wipe it from his cheek with a handkerchief, also now takes a swing at the evil father who abuses his own daughter. He’s a bit more pro-active in 2018.

Think of Atticus Finch. He’s so well known in fiction that the poster for this revival-new production-whatever that he’s featured on the poster with his portrayer, Jeff Daniels. You rarely see a poster like that. It’s Jeff Daniels as Atticus Finch, as if Atticus had been a real person. He was Harper Lee’s creation, but like Holden Caulfield and Quentin Compson, he’s fixed now in the public imagination.

Sorkin has sucked in the novel like a high speed vacuum. He’s consumed it. Not only the novel, but the Robert Mulligan movie, and the specious sequel, “Go Tell a Watchman.” After seeing “Mockingbird”last night at the Belasco, I have this idea that Sorkin is lying on the floor collapsed under a blizzard of Post Its and index cards. He knows more now about Maycomb, Alabama than anyone who was born there. He knows every corner, every minor and terciary character, whether someone sneezed and if Scout saw it. We are not worthy.

Sorkin’s “Mockingbird” is the most comprehensive study of the birds of Alabama — Finches, mockingbirds, all of them — you could hope to find. He’s picked new supporting characters from the novel to highlight, and even combined a couple. Everyone’s a little mouthier now, and there’s some explaining going on that we never needed before. That’s why this is almost three hours including intermission.

But you don’t get “The West Wing” or “The Social Network.” The pace is languid, for Sorkin. The old rat-tat-tat is missing, a good thing. He gets their cadences, and director Bartlett Sher lets everyone take their time telling the stories of Atticus, his kids, Tom Robinson and Boo Radley. Sorkin also breaks up the chronology of the book and the movie, making Tom’s trial the opening scenario and then suspending it to fill us in. Sorkin grabs us by the lapels and drags us into these people’s lives.

Jeff Daniels worked with Aaron Sorkin on “The Newsroom” TV show, so they know each other well enough. Daniels is not Gregory Peck. He lumbers on stage. He gives such a knockout performance, you’ll never think of him as anyone else. The Finch children are played by adults here– it reminded me at first of “You’re a Good Man, Charlie Brown.” But Celia Keenan- Bolger, Will Pullen and Gideon Glick are nimble as adults conveying pre-tweens. Keenan-Bolger makes for a masterful conscience and point of view narrator. Maybe the hardest role is Bob Ewell, the villain. If you get that right, you’re in. Frederick Weller is superb.

In the movie, the black people barely spoke. Here, Sorkin has given them a lot to say, especially Tom (Gbenga Akinnagbe) and finally Calpurnia the nanny-maid-housekeeper. She is now described akin as a sister to Atticus. LaTanya Richardson bides her time, and for a while I wished she was more voluble. But Sorkin saves her for last– and in the final part of the second act we get a new Calpurnia, who speaks as an equal. Richardson is dynamite, saying all the things now that Calpurnia has probably been thinking all these years.

Any quibbles are minor. Sorkin has added quite a bit of joking around. Some of it seemed a little sit-comy. A couple of routines that landed in punchlines almost threw off his rhythm. But as a woman sitting next to me said at intermission, the story is so awful, you need a little relief every now and then. I’ll go with that.