Fayson has always wanted to be a detective. When her cousins recruit her to their top-secret gang on the island one summer, her dreams seem to be coming true.But the Greatest Gang of All Time don't live up to their name, and keep getting distracted from missions by things like food, falling asleep and a fair bit of squabbling!Guided by her favourite mystery novels, Fayson takes charge and tries to track down clues about the strange shadow that has been appearing in the island's lighthouse.With tensions stirring within the gang, can she use all her smarts to solve the case?