Plot (Spoiler)

When Peter and the guys try to salvage a sunken Mercedes-Benz, Peter half-heartedly promises a favor to a helpful dolphin named Billy Finn (guest voice by Ricky Gervais). Soon, the dolphin moves to Quahog but outstays his welcome at Peter’s, so Peter tries to reunite Billy Finn with his ex-wife (guest voiced by Lucy Davis) in hopes that he will return to the ocean. Meanwhile, Stewie is attending a pre-school with an incompetent but pretty teacher who Brian falls for.