The Righteous Gemstones Kicks Off Final Season With Surprise Prequel Starring... Bradley Cooper!

Fans of The Righteous Gemstones tuning in to the HBO comedy's fourth and final season premiere Sunday likely suffered a major case of whiplash. The modern-day evangelical farce starring Danny McBride, Edi Patterson, Adam DeVine and John Goodman was, for all intents and purposes, gone, replaced with a Civil War-era, faux biopic headlined by 12-time Oscar-nominated actor Bradley Cooper.

The super-sized, standalone episode — arguably the boldest creative swing in Gemstones' history —functioned as a prologue to the show, one that explored the Gemstone family's twisted, corrupt religious roots, circa 1862. According to McBride, Cooper's casting as the brood's OG ecclesiastic began as a pipe dream.

"We needed somebody that had a certain charisma and charm, someone the audience wouldn't mind going on this journey with, somebody that could hold the entire thing on their shoulders, and I think I just [blurted out], 'You know, somebody like Bradley Cooper,'" McBride shared earlier this week at Gemstones' Season 4 premiere in Los Angeles. "And my producing partner, Brandon James, was like, 'We should just ask him.' And so we just sent him the script and he responded really quickly that he was interested and wanted to do it."

Added McBride: "I knew it would be a tough role [to fill], because this show is, obviously, an ensemble. There are so many incredible actors that the audience is showing up for. And to invite the audience back after the show's been off the air [for nearly two years] and not have [them see] any of the beautiful faces [of the regular cast], it just had to be somebody that was more beautiful than all of us put together."

The Cooper-led prequel sets the stage for a closure-filled farewell season that, per McBride, was not guaranteed to be a farewell season right out of the gate. "We weren't sure what we were going to do," he admitted. "When we started writing [this season], a lot of the themes that were coming to our brains [involved] moving on. So we were kind of aware in the writers' room that this was probably the end. But I wanted to keep an open mind while we were shooting just in case it didn't feel like that, or [in case we] tanked it and wanted a chance to redo it [in a potential Season 5]. But as we moved through the season, it became aware to me that we had completed what we had set out to do."

McBride, however, did not share this fluid intel with his fellow castmates until after Season 4 wrapped. "Sometimes when you know it's the [final season] you can see it on the actors' faces; everybody is sad and saying goodbye to these characters [in their performances]," he noted. "I thought it was important to make sure this season felt as authentic as every other season felt, and that no one would carry that baggage throughout the season."

Want scoop on The Righteous Gemstones, or for any other TV show? Shoot an email to InsideLine@tvline.com, and your question may be answered via Matt's Inside Line!