Tiril and Oliver are out camping with Ocho when they spot a light winking in one of the windows of the dilapidated old castle out on Ormøya. To find out what’s going on, the two young detectives will have to uncover clues, solve riddles and decipher codes. The search for answers will take them through secret doors, damp cellars and dark passageways in the mountain. And the reader is welcome to join them! Just remember to keep your eyes and wits about you – the answer might be hidden on the next page.

The Search for the Castle’s Secret is the fourth activity book in the Detective Agency No. 2 series.