At the hotel "By the Crab" on the island of Norderney, there seem to be ghosts, and therefore no one stays there. While Dad Mick checks into the hotel, Emma and Lucas set up an ambush around it.
It's great that Cousin Uncle Janssen has equipped a detective van perfectly for such occasions. It has literally everything, from all sorts of technical novelties that allow you to see and hear literally through walls, to an impressive stock of food that may come in handy during the many days of surveillance over the criminal.
And the ghosts do not make them wait. The walls tremble and shift from their howling and clatter. They scare Dad Mick so much that he leaves the hotel in dreadful panic. But it's not so easy to scare Emma and Lucas. Moreover, they suspect that behind the guise of ghosts, unscrupulous and cunning people are surely hiding. They return to the hotel and, risking their lives, not only expose the criminals but also save the life of a noble elderly lady.
The key to success in the investigation is simple: Emma and Lucas are observant, clever, and fearless. And they complement each other perfectly. Moreover, the fact that they are still children only helps them get into places where not every adult would venture.
Engaging plot, likable characters, and excellent translation by Pavel Frenkel guarantee reading from the first to the last page in one sitting.