Timmy is a six-year-old boy who loves adventure. Today he is excited. Today is the day he is venturing into the ocean for the first time to explore the underwater world.

As Timmy first dives into this new world, he is fascinated by the colours and creatures he sees. During the story, Timmy makes an unlikely friend, a young and frightened hammerhead shark named Henry. Henry is frightened because he has lost his mother. As Timmy learns the sad story of what happens to Henry's mother, he becomes determined that he must help his new friend.