The premiere opens in a post-apocalyptic wasteland where the Comic Center of Pasadena is (somehow) still standing. There, Stuart and Bert are visited by another version of Stuart — presumably from the original “Big Bang” universe — who informs them that Leonard, Sheldon, and Howard built a machine capable of restoring reality to the way it was.
It’s an effective inciting incident, but it’s also something of a red herring. Whether or not Stuart is the “chosen one” destined to set things right is almost beside the point — at least initially. In short order, Stuart and Bert reunite with Denise and Kripke, and the quartet begins traversing the multiverse, encountering alternate-universe versions of familiar characters along the way — and not just the ones you’ve already seen in the trailers.
The version of Stuart we first meet in this dystopian hellscape is every bit the same character he was when “Big Bang” ended in 2019, accepting of the bum hand life has dealt him — especially here, in a parallel universe where unflavored floss is considered a luxury. But there’s also a bit of that early confidence the character had when he was first introduced in Season 2 as an unknowing threat to Leonard and Penny — a quality that gradually resurfaces the deeper into the multiverse our reluctant hero ventures.
Kevin Sussman — who, in an alternate universe, could very well have been cast as Leonard Hofstadter — proves a fitting (if atypical) leading man, with his knack for deadpan on full display from the jump. Stuart always seemed to be hanging on by a thread — especially before he met Denise — and when his sanity is greatly challenged in Episode 4, Sussman makes a meal of the opportunity.
Brian Posehn, meanwhile, settles comfortably into a role Bert never occupied on the original series, serving as Stuart’s best friend while also becoming — in one of the season’s funniest recurring gags — a quiet cheerleader for Stuart and Denise’s relationship in every universe they encounter. Posehn has long been a master of underplaying even the most heightened situations, and he brings that same sensibility here. But as the season progresses, he also subtly modulates Bert’s reactions to his ever-changing surroundings, resulting in some of the biggest laughs of this freshman run.
As Sheldon Cooper’s one-time nemesis Barry Kripke, John Ross Bowie has perhaps the most difficult task at hand — taking a character who would be considered an imbecile in any universe and making him someone the audience wants to spend significantly more screen time with. What makes it work isn’t so much that the writing for Kripke has changed, but that Kripke seems more aware of how off-putting he can be, and embraces it. That said, when the others call him out for putting any one of them in danger, he at least seems aware he’s done wrong, if not exactly remorseful.
Meanwhile, Lauren Lapkus benefits from playing the least-defined member of the quartet. Denise appeared in just eight episodes of “Big Bang” during its final two seasons, giving Lapkus the widest canvas on which to paint. Without spoiling too much, let’s just say the version of Denise we meet in Episode 1 isn’t necessarily the one who follows in subsequent episodes, leading to an existential dilemma that gives Lapkus a lot to play with come Episode 3.
The seemingly endless parade of alternate realities also gives the series license to resurrect beloved “Big Bang” characters in ways that feel playful rather than obligatory — helped by the fact that none of this is considered canon. The cameos are plentiful — if you saw my July 2025 interview with Lorre, in which I repeatedly poked and prodded about returning cast members, you can probably make some educated guesses — but they’re always in service of the story at hand, never shoehorned in simply to generate headlines. In fact, you may be surprised by how sparingly certain alumni are ultimately used. But because each appearance serves a distinct purpose, you won’t find yourself missing them when they’re gone. And because only our central quartet travel between universes, many of those returning actors get the opportunity to play multiple versions of the same character — one of the most enjoyable byproducts of the show’s premise.