In the town of Mossingham, The Farmer and his dog, Bitzer, discover the landing of a UFO. On nearby Mossy Bottom Farm, Shaun and the flock attempt to pass time with several dangerous activities, only for Bitzer to stop them. After being banned from having a barbecue for dinner, Shaun decides to order three pizzas, but when the pizzas arrive, both Bitzer—who intercepts two-thirds of the delivery—and the flock discover the pizza boxes are completely empty.

The next morning, Shaun discovers a trail of pizza crusts and encounters the visitor. The visitor introduces herself as Lu-La, an impish alien from the planet To-Pa who can mimic sounds and levitate objects.