Gertrude Chandler Warner

The children are attending Camp Coral, where they learn about the ocean and all the things in it — coral, fish, dolphins, and other sea creatures. They find a beautiful hidden beach, but then learn that it holds a terrible secret. Once again, the Boxcar Children must come to the rescue!

While visiting their aunt and uncle in San Francisco the Alden children visit Fisherman's Wharf. After they ride on their uncle's boat they discover something fishy is going on in the wharf and someone doesn't want Uncle Andy to catch any fish.

Someone steals the newly refurbished boxcar the Aldens are going to ride at the Greenfield Founder's Day Parade, they only have a couple of days to find it before the event.

Unusual events start when the Alden children assist with a dinosaur exhibit opening at the Pickering Natural History Museum.