The warm, tingly feeling that had been smack in the middle of Alvin Fernald's stomach ever since Miss Peppersmith had closed and neatly lined up her books that Friday afternoon, had grown bigger as he and Shoie walked home from school. Now, here, in his hand, was the reason why!...
Twelve-year-old Alvin and his best friend Shoie use their knowledge of codes and ciphers to solve a dangerous mystery.