Alexander, 13 years old, attends secondary school. He goes to the same class as his best friends Maulwurf and Lotte. Maulwurf is a tinkerer. He constantly invents new things. The mother-of-pearl colour is a very special creation. When you apply it on paper and leave it to dry, the paper appears to be almost transparent, with a special lustre.

The holidays get off to an exciting start for Tarun and his girlfriend Alice, because top secret documents are stolen from Tarun's mother Jaswinder's research base in Ireland. As a dedicated marine researcher, Jaswinder is working on a project that aims to reduce plastic waste in the oceans.