Travel to the beautiful, flower-filled country of the Netherlands for an artistic adventure that quickly turns into a major missing persons case. While Violet is happily taking an art class to improve her painting skills, her friend's father mysteriously disappears without warning. The missing man is a renowned botanist, and his sudden disappearance seems directly linked to his top-secret research on the extremely rare black tulip. The Thea Sisters know they cannot waste a single minute. They set out on a desperate search that takes them past giant windmills, down quiet water canals, and through massive, colorful flower gardens. As they gather clues hidden among the blooms, they must figure out who would want to steal the famous flower and kidnap a scientist. It will take all their puzzle-solving skills to crack this floral mystery.