Junior's in the middle of the ocean, collecting flowers for Casey. He comes across Shellshock, a giant red dragon who is supposedly the most feared monster in the sea. He fights him off, which makes Daffney and Casey immediately fall for him. Turns out this was only a story Junior was telling Willie. Then he talks about his Shalloween party, which Willie isn't invited to because he can't be scary enough. Willie decides to go after Shellshock to prove to Junior he can be scary enough for Shalloween.
Meanwhile, Allstar and his friends are preparing to go the Junior's house for the Shalloween party. Allstar's dressed as a snorkeater; Casey as a sea witch; Daffney as a sea devil; and Tooter as a giant gray fish who roars. Willie, dressed as a blue dragon, swims to them asking where he could find the Lost Valley to see Shellshock. Allstar laughs and says he's too young for that sort of thing. Then they head over to Junior's, who's dressed as an underwater vampire. After a tour around Junior's house, they enter Willie's room, where they see a drawing of him REALLY going to find Shellshock.
Allstar and his friends, who left Junior behind, try to find Willie in the Lost Valley. Tooter keeps foiling them, at last before they encounter the REAL Shellshock. He's about to eat them for dinner when Willie comes up to them. Shellshock claims he had no friends until he met him. The gang cries at this touching story, and then he confesses he's really a vegetarian. Shellshock takes them home, and Willie brings him to the party.
|Michael Bell||Allstar Seaworthy|
|Patricia Alice Albrecht||Additional Voices|
|Rene Auberjonois|| Dr. Strangesnork|
|Nancy Cartwright||Daffney Gilphin|
|Cam Clarke||Additional Voices|
|Laurie Faso||Additional Voices|
|Barry Gordon||Junior Wetworth|
|Gail Matthius||Baby Smallstar Seaworthy|
|Edie McClurg||Mrs. Seaworthy|
|Rob Paulsen||The Snork Patrolman|
|B.J. Ward||Casey Kelp|
|Fredricka Weber||Willie Wetworth|
|Frank Welker|| Tooter Shelby|