The Griffin family looks forward to the annual Christmas carnival at the Quahog mall. When they arrive at the mall, there's nothing festive going on at all. It's canceled.
Vinny, who still doesn't quite fit with the family and has yet to form a truly cohesive friendship with Stewie, finds out that Carter Pewterschmidt, Lois' jerk of a father, runs the mall and axed the carnival. Peter visits the cranky old man hoping to get an explanation. Carter says he canceled it because he hates Christmas: when you're rich, everyone expects you to buy something great and you get nothing.
The Griffins worry that Stewie will dwell on the fact that the carnival was canceled; he seems really broken up. After some sexually explicit convincing from Peter (and telling him people assume him to be Jewish), Carter brings back the carnival.
Even with the return of the carnival, Stewie seems very bothered. When he hops on Santa Claus' lap, his sadness is apparent: he wants his friend back. That's right, Family Guy fans, Stewie misses Brian the dog!
Is this the glimmer of hope viewers have been wishing and tweeting about?
Vinny tries to make Stewie feel better by giving him some Christmas presents to open. When that doesn’t work, Vinny offers to buy Stewie a toy. At the toy store, Stewie sees himself from the past that had time-traveled ahead to make a purchase.
Stewie realizes that the past Stewie has a time travel pad. The current Stewie’s time travel pad had been destroyed before Brian got killed by a speeding car. After a distraction by Vinny, current Stewie plans to go back in time with the pad to save Brian. It's bye-bye for Vinny and it's at this moment that his departure actually seems sad. The new dog was beginning to fit in.
Back in time, current Stewie saves Brian from getting hit by a car. Current Stewie fades away because history has been altered. But that's OK. Brian is alive and the past Stewie carries on like nothing's happened. They're such best friends, Stewie greets Brian with a "Game on" shout and hits the beloved dog between the legs with a hockey stick.
Brian gives Stewie a photo of the two of them for Christmas; it says "Friends Forever." All is right in the Family Guy world.