When a fire at the retirement home forces Grampa to move back in with the Simpsons, Homer throws out his back on moving day. While "resting" at home, he gets hooked on the super-addictive tablet game, "Villageville." And, in his distraction, he loses the family dog, Santa's Little Helper. Everyone is angry with Homer for not seeming to care about the missing dog, but Grampa tells them the story of Homer's long-lost childhood pup, Bongo,.