After Alvin loses Lucy, Simon's fish for his science fair project, he suggests they get a job working at an aquarium. Alvin takes care of baby hurmy, a humpback whale, while Theodore trains the seals. Max, a former employee who was fired for mistreating the animals, shows up wanting his job back. Meanwhile, Simon's studying the dolphins while Max develops a plan to kidnap one of the dolphins and hold it for a $25,000 ransom. Simon conducts a recording experiment to find the other dolphin. Once it's safe, they all go after Max and celebrate with a special performance at the aquarium.
- "The Boys are Back in Town" originally performed by The Busboys.