Penelope Kingston is the ONLY person who has managed to avoid the dreaded crush plague sweeping Chelsea Primary. Almost all of her friends have crushes – even her brother has been infected! Penelope is excellent at figuring most things out, but crushes are a Great Mystery to her. Luckily, she has come up with a quiz to diagnose crushes early, before they have a chance to make people Very Silly. But what happens when the quiz shows that one of Penelope's favourite people clearly has a crush on her?