The episode starts on Tegridy Farms where Jimbo and Ned are hunting. They find strange bear prints, and decide to follow them, until they are spotted by Randy and Stan, the former of which starts berating them until a pig roar is heard. Ned, scared, runs away, and is captured by ManBearPig, as the others look on in fear.
Yates investigates at South Park Elementary and finds the kid's body ripped apart on the ground. He still continues to believe that this was a shooting and brings Cartman and Kenny, "the two biggest loners", in for questioning.
Stan tells the boys that the kid was mauled by a creature, worried it was coming after him. At Kyle's house, Stan and Kyle investigate what the creature might be, and discover it was Manbearpig. Stan realizes they were warned about it, and go in search of Al Gore.
Sergeant Yates gives another report at the police station, insisting Cartman and Kenny are kept in separate cells. He again tries to leave to play Red Dead Redemption, but is informed of more dead kids at Stark's Pond, which, even though it was outside the school, he still believes was a school shooting.
The boys search for Al Gore leads them to Gramercy Lanes, where he is a bowling champion. They tell him that he was right about Manbearpig and ask him for help, which he refuses. He tells them to apologize and, when Cartman does, he believes it wasn't sincere.
At Red Lobster, a man speaks to his wife about Manbearpig. He explains that, even though some people believe in it, doesn't mean it's real. He boasts his opinion that it is made up, while Manbearpig breaks in behind him and starts attacking people. When he notices it, he questions what they can do now that will make a difference, before being killed by it.
The boys throw a party for Al Gore at Olive Garden to convince him to help. This includes a lot of food, a song and a video of clips of real-life Al Gore in the past. He then tells them this was just to apologize for them making fun of him. He mentions he plays Red Dead Redemption 2 but doesn't know how to sell items, so the boys agree to help.
At Baskin Robbins, the cops investigate another attack. Sergeant Yates find out Cartman and Kenny are on the run with Stan and Kyle, and tell all cops to try and find them. Another cop convinces Yates to go home and relax with some Red Dead Redemption.
Al Gore takes the boys to his secret research storage locker, where all information on Manbearpig is. He tells the boys that Manbearpig is actually a demon, and says that they need to do a demonic ritual.
Sergeant Yates arrives home to his wife, and starts playing Red Dead Redemption 2. Maggie Yates asks him to come have lunch with her. Harrison Yates then notices his game has been played since he last played, and discovers Maggie has played some without him. Angry, he starts a new save game.
In the woods, Al Gore and the boys perform the demonic ritual. He tries to get the boys to say he was right again, and Stan snaps, annoyed that he doesn't know what he's doing, before the ritual begins, leading him to have to apologize again. Satan is summoned and tells the group that, to find out about Manbearpig, they need to go to the library.
At South Park Public Library, Satan finds out Manbearpig came because of a deal that was made with someone in the town. The library is then surrounded by cops, headed by Yates, still angry over what his wife did. By instruction of Al Gore, the boys go outside to convince the town that Manbearpig is real and people need to take action now. Yates doesn't listen and gets the cops to lock the boys up, before leaving to play Red Dead Redemption.
At Shady Acres, the old people watch the boys getting arrested on TV, with Stan telling people someone made a deal with Manbearpig. Marvin Marsh is horrified, asking himself what he has done, suggesting he did the deal.
AV Club gave "Time To Get Cereal" a "B" rating saying: "The bits with Gore are a bit frustrating, but this was about as clear of an admission of guilt as you could get, and when you consider that no one was really asking them to make this episode, the fact that they took it upon themselves to do so is an admirable display of responsibility. We’ll be able to get a greater idea of the degree which this episode succeeds or fails when we see how it fits into the rest of the season. For now, though, as a long time South Park who has spent over a decade confronting the dangerous implications of “ManBearPig,” it was enjoyable and cathartic to see Trey and Matt admit they were wrong."
IGN gave "Time To Get Cereal" a "9.1/Editors Choice" rating saying: "Before this episode, it might have seemed like there was nowhere left to go with Al Gore's anti-ManBearPig crusade. "Time to Get Cereal" proved how wrong that is by taking full advantage of Gore's return and the climate change metaphor at the heart of his nemesis. Coupled with the welcome return of Satan, some great Red Dead Redemption humor and the start of a new multi-part storyline, this episode raised the bar again for Season 22."