What is the book about? Let's see.
Two sisters - Adi and Nina live in a neat house beside the lake with their parents. One morning Adi, the older girl, wakes up and can not find her teddy bear, nor her little sister.
Looking everywhere in the house, she grabs her sister's teddy and jumps in the boat near the house. She travels in the boat looking around with her binoculars when suddenly something lifts the whole boat. Adi thinks the boat floats on a giant wave but it turns out the wave is an angry shark.
The shark has just waken up and doesn't like to be disturbed early in the morning. Adi, who is not very frightened, because she is a bold little girl, manages to stay in the boat.
The shark twists and turns until the boat lands on a small island with beautiful big red flowers. In the distance Adi sees a structure that reminds her of a water slide. When she approaches, she sees her little sister Nina, sliding with Adi's lost teddy.
Nina sees her sister, runs to her, hugs her and they exchange the teddies. Then they play in the water for the whole day. When evening comes, they go back to their parents who have been very worried about the disappearance of the kids. Lastly, they hug Adi and Nina and the kids promise always to inform their parents before going out.
All is safe and sound.
The End. :)