Grace Garcia, her brother Louis, her best friend Caitlin, and Caitlin's dog Diego are kidnapped by a man calling himself The Watcher while visiting a store in Venice, Italy. The Watcher takes them to Rome and then Paris, holding them captive. The children work together to escape, finding food and water with the help of a doe in the forest. They make their way to the police and identify their kidnapper as John Cashy, using details they overheard. Police pursue Cashy and arrest him. The children are reunited with their parents and given a holiday in Paris by the police before returning safely home to Venice.