Jed tells Elly and Mark why Granny doesn't like him – she thinks Mark is half frog and can change others into them by getting them into the pool. Jed tells Granny, who has been feeding Jethro breakfast, to go to the pool with her. She thinks he is going to kill her. When they get there, Mark takes off his frogman suit, and Granny finally believes he is 100% man. From then on, she is set on getting Elly and Mark married. As Granny is making her plans, Mark tells Elly that he is going to leave the Navy to pursue the oceanography research.
At the bank, Drysdale plans to take control of the money for the research, and tricks Mark into getting the check. Jane quits and says how she is going to the beach where the grunion are running. She also reminds Drysdale how when Mark goes on with his plans, he is through. Drysdale realizes he has to keep Mark in the Navy. He uses the Grunion Invasion headline on the newspaper to make the Clampetts believe the island of Grun is invading California, and Mark is leaving the Navy so he doesn't have to fight. Jed calls and asks if he knows about the Grunion, and Mark says he wants nothing to do with it. Jed thinks Mark has turned into a coward, and when Drysdale leaves, the Clampetts prepare to fight the Grunions.