Cookie and Hilton Chan are 15-year-old twins whose father is the chief criminologist with the Hong Kong Police Department. After a brush with death during a windsurfing competition, Hilton goes looking for a good luck charm at a curiosity shop in Stanley Market. He stumbles upon a relic that just might be the clue to a legendary pirate treasure, lost for centuries. Arriving on Cheung Chau Island, the quest moves into high gear. The twins soon discover they are not the only ones in the hunt. The two adventurers must decipher the clues, trust their instincts, and employ their youthful imaginations to survive the dangers from pirates both ancient and modern day. Will the twins prevail? Will the code be cracked? Will the secret finally be revealed?