Otto von Finkenstein, the old riddle count and builder of Finkenstein Castle, is said to have been a murderer? No way! Anna, Fred and Grandpa Drechsler, who have already followed Otto's footsteps, mobilize all their puzzle knowledge to get to the bottom of the matter. And for that they don't sit at home in Finkenstein, but travel across Granada and right into the heart of the Alhambra.

Anna and Fred have to rush to Grandpa Drechsler's help, because he is to be thrown from his place of residence at Finkenstein Castle. The young heir wants to turn the property into a golf park and not a museum for puzzles and secret writing, as the faded Otto von Finkenstein wanted. Unfortunately, he didn't leave a will about it. Or is it? Anna, Fred and Grandpa Drechsler want to find it and the fact that Count Otto was a first-rate puzzle fan makes the three of them work up a sweat.