Olli, the curious little octopus lives in the ocean. He explores his watery world and makes many friends that way. He goes to school with a group of guppies and all think it is really cool. Their teacher is a mermaid. She is King Neptune's daughter. On her birthday there is a big celebration and all are invited.

When they meet a scary shark Olli learns that he has something n his body that helps them to escape.

Follow up with book two and three to read more about Olli's adventures, alone or with his friends and teacher.