"I'm at that special age: 12. It is one of my favourite numbers in the whole universe. In fact, it's my perfect number. 12 isn't just the sum of 10 (the base of our whole amazing number system) and 2 (the only even prime number in the cosmos) but it's the first number with 1, 2, 3 and 4 as factors. I reckon that's so cool." Eliot thinks outside the box. He can't help it. Numbers are his thing - and letters, too. So when the biggest mystery that struck his school in the history of the world needs to be solved, Eliot is the one to call on. Can you solve the mystery and find out who did it - before Eliot does? This time the solution isn't in the real world (the 'real' world of the story). Instead it's inside the book itself - locked away in a series of puzzles. Can you find the clues, solve the puzzles and find the culprit?