The Case of the Oxygen Theft

Brian and Aapchi — very polite aliens with a very dangerous plan. They want to build a resort… and drain oxygen from the planet's atmosphere. Their cruiser is already hovering in the stratosphere.

No one on Earth knows about this. Almost. Thirteen-year-old Anna feels that the world is in danger. Together with her best friend Mia, she starts an investigation — and all they have as their first clue is a wrecked playground. Funny? Only at first glance.
The girls notice the little things, ask uncomfortable questions, and step by step piece together the picture… But will the young detectives be able to thwart the aliens' plans?