Secret of the forgotten shore is an adventure story .The story follows Sean Anderson, who receives a coded distress signal from a mysterious island that doesn't appear on any map. Convinced that the signal is from his missing grandfather, Sean teams up with his stepfather Hank, and together they travel to Palau. There, they hire a helicopter piloted by Gabato and his daughter Kailani to reach the island.
Upon crash-landing, they discover a strange world filled with enormous creatures, such as giant insects and oversized lizards. They soon find Sean's grandfather, Alexander, who reveals that the island is rapidly sinking. To escape, they must locate Captain Nemo's legendary submarine, the Nautilus, hidden somewhere on the island.
The group embarks on a perilous journey across the island, facing various dangers along the way. They eventually find the submarine and manage to escape just as the island is submerged underwater. The movie ends with the family returning home safely, hinting at future adventures.