When Cam Jansen, her father, and her friend Eric go to the library, Cam finds a mystery to read. But soon, she has a mystery to solve. Her father's shopping list has disappeared. Cam decides to use her amazing skills to investigate, and with a click, she puts her photographic memory into action. Where was the list seen last? And where can it possibly be?

To celebrate their 100th day of school, Cam and Eric's class party will have snacks that start with "P"--pretzels, popcorn, pineapple juice, and pizza. But when the pizza disappears from the kitchen, it's up to Cam and her photographic memory to solve this delicious mystery.