While visiting the Clevelands in Stoolbend, Stewie and Oscar stumble across a secret weapons and surveillance room in the basement. They find a video tape showing what happened to the real Cleveland Jr...
The Griffins are invited to see Peter's old friend Cleveland Brown and his family in Stoolbend. They pack to go, but Lois mentions that they need space for two booster seats because Oscar is with them. They drive off with Meg tied to the roof.
The Griffins arrive at the Cleveland homestead and everyone greets each other. Stewie and Oscar decide to explore. They find a secret panel in Cleveland Jrs room that leads to a weapon and surveillance room. Stewie is jealous and remarks he'll be upgrading his war room when they get home. Oscar finds an incriminating video of Fat Cleveland Jr murdering the original hyperactive Cleveland Jr. They're then caught by Cleveland Jr who holds them at gun point and keeps them prisoners so they never speak a word about what they saw.
Meanwhile Peter screws up dinner as usual and starts a fight with Tim the bear because he thinks having a talking bear was an even stupider idea since Roger the Alien.
Elsewhere Stewie and Oscar escape their ropes and confront Cleveland Jr. They have a fight (like Evil Stewie vs Stewie and Stewie vs Penny) and eventually over power him.
After a cutaway gag Oscar and Stewie debate how are they gonna clean up fat Cleveland Jr's mess. Stewie reminds him that he has a time pad for impromptu time travel when his main time machine is unavailable. They travel back in time, unaware Cleveland Jr also has a time machine.
They arrive just before Cleveland Jr is about to kill the real Cleveland Jr. They fight him two on one until future Cleveland Jr arrives to even the score. The Clevelands are almost losing until Future Cleveland Jr tries to shoot the real Cleveland Jr but Oscar pushes him away and takes the shot and is fatally wounded. Stewie in anger kills both fat Clevelands. The timeline resets and sends him back alone.
Stewie finds things very different now that thin hyperactive Cleveland Jr is still alive and Oscar returns revealing his own timeline is so messed up that he can't be killed. They then ponder if they did the right thing and whether them changing time will have repercussions.