Penny Warner 
Haunted Lighthouse [PDF ebook] 

An infamous prison may hold a secret only the Code Busters can uncover. Cody, Quinn, Luke, and M.E. may all have different talents, but they share one thing in common: they love playing around with codes. In fact, they love codes so much, they have their own club, with a secret hideout and passwords that change every day. When Cody and her friends get a mysterious e-mail hinting at a treasure on Alcatraz Island, they can’t wait to get started on their clue hunt. Luckily, a class trip to the prison is the perfect cover to start their search. During the tour, the club members learn that a jewel thief kept at Alcatraz may have hidden his biggest haul on the island and left a series of coded messages to find it. And solving puzzles is what the Code Busters do best! This interactive mystery features more than fifteen codes and puzzles for you to decipher along with the Code Busters, including Morse code, the tap code, LEET, and zigzag code. Answers are in the back, if you ever get stuck.