Paula is the puzzle queen of the campsite. When her friend Suse finds a mysterious love letter without a sender in front of her caravan one morning, it seems that Paula's big moment has arrived: This is clearly a case for a savvy detective! It's double luck that Paula has just met Toni, who is not only really nice but also shares her love for unsolved puzzles. Together, they set out to track down the mysterious author of the letter. There's just one catch - Paula wrote the letter herself. However, it wasn't addressed to Suse... In lively illustrations, Sandra Brandstätter takes her readers on an exciting and humorous summer of sleuthing.