The Reed brother's Aunt Cleo comes for a visit, concerned about how her nephews are getting along. Tim, with Salty, takes his aunt around the islands to give her an idea what his life in like.
Tim and Rod, along with Salty, head out for a day of exploration. They find a large deserted house and while checking it out the two pals get trapped in a freezer. For any rescue the boys must depend on the seal Salty.
The boys set out for a day of adventure with Salty who leads them to a seemingly deserted lighthouse. The two friends meet a unusual older man who asks the lads to keeps his whereabouts a secret.
Trumbull, an unscrupulous businessman, wants Clancy's marina for development. He starts to put pressure on Clancy to sell but the Reed brothers urge Clancy to resist.
Clancy 's former girlfriend Maggie, a NYC lawyer, returns to the island. Clancy faces a dilemma when Maggie tells him she still cares for him and wants Clancy to live in the city with her.
A professor named Jerry intends to use Salty for possibly dangerous experiments so he can achieve tenure. The Reed brothers must find a way to rescue Tim's pet seal before any harm occurs.
Starwell has brought his seriously ill daughter to the island, believing nature wil help her get better. The Reed brothers become involved when it becomes clear the young lady needs a doctor's attention.
Linda is a marine biologist who meets Taylor, Tim, and Salty in the course of her job. The scientist begins encountering problems when two criminals try to keep her away from a certain part of the ocean. The Reeds and Salty help find out why.
Rod is kidnapped and held prisoner on a boat. The kidnappers force Rod's father to participate in a bank robbery. Salty finds Rod and tries to lead others to his rescue.
Tim is hungry and starts looking around for something to eat. He devours some leftovers he sees laying out and then leaves with Salty. Taylor realizes his brother ate spoiled food and begins a frantic search for Tim.
A young Stanley just moved to the island with Tim making fun since the new boy is afraid of Salty and the water. Taylor and Clancy recall for Stan how withdrawn and scared Tim was when he first arrived at the marina.
Two men see Tim with Salty and are amazed at what the seal can do. They plot to steal the marine animal and sell it to a circus. It's up to Tim plus his pet the foil the plan.
Visiting kids see a plaque that attracts their attention and decide to take it. The older man whom it belongs is devastated as the item has sentimental value. Tim and Rod decide to find the plaque and return it.
A criminal duo has found some valuable artifacts but can't get them off the island. They stash the items on Taylor's skiff where authorities find them and Taylor has no explanation. Tim and Salty work to clear the older brother.
A visiting sea lion appears on the scene and get plenty of attention from the Reed brothers plus their biologist friend Linda. Salty decides to withdraw thinking he's unloved. His human pals must show the seal how important he is.
