One summer on Lake Springfield, members of rock band Green Day fail to engage the audience in a discussion about the environment. They are killed when the pollution in the lake erodes their barge, sinking it. During their memorial at Reverend Lovejoy's Church, Grampa Simpson has a spiritual experience and frantically prophesies that a disaster will befall Springfield, but only Marge takes it seriously. Lisa and her new friend Colin, whom she has fallen in love with, hold a seminar where they convince the town to clean up the lake. Meanwhile, Homer adopts a pig from Krusty Burger. Marge identifies the pig as a part of Grampa's prophecy and warns Homer to get rid of it, but Homer refuses. Homer's fawning over the pig makes his son Bart (who is now jealous and fed up with his father's carelessness) look to their neighbor, Ned Flanders, as a father figure.