After taking bad advice on football gambling, Homer is in debt to the mafia who loaned him the money. To repay them, he lets them shoot a "gentleman's film" at his house. Homer sends Marge and the kids off to "Santa's Village" while this is going on, however, Marge finds out when they return early.
She leaves in a fit of rage and ends up at the beach, where she meets Caleb Thorne, a marine biologist trying to save the endangered manatees. Marge takes a shine to Caleb, even though he seems to care too much about his mission. She decides to join him and take a chance to find herself.
Meanwhile Homer searches for Marge, and ends up staying with a 'country cousin'. When he eventually finds her he apologises, but Marge won't take him back so easily. Homer decides he must help save the manatees to win her back. After a run in with some jet-skiers, Marge sees that Homer is 'the real endangered species' - a devoted husband and father.