Stanley, Charlotte, Gertie, and Felix are just your typical twelve-year-old kids. They love hanging out after school. They love burgers and milkshakes. And they love math. And if there's one thing they love more than math, it's solving mysteries! Thankfully their hometown has plenty of mystery and quite a few secrets. Aligned to Common Core Standards and correlated to state standards. Chapter Books is an imprint of Spotlight, a division of ABDO.