Irwin always feels mysterious about the ocean. Each summer, he will visit his uncle, Dr. Orca, to explore the ocean deep. On a rare occasion, Dr. Orca's underwater hydrophones detected an unusual signal sounding more than 3,000 miles away from the source. Unfortunately, everyone dismissed their discovery as some natural phenomenon. So, Dr. Orca, Irwin, and Shelley decided to get closer to the source for evidence. Too bad, the signal was no ordinary signal... Beneath the ocean laid a century-old legend... Just another urban legend, right?