Ms. Abaza's fifth-grade class is beyond excited when she brings in live mice for them to care for. The students spend the day thinking up names for their new furry friends. Should they be named after soccer players or computer scientists? The possibilities are endless! Yet when the students arrive the next day, the mouse cage is empty. Did an animal-loving vegan set the mice free? Or were they mouse-napped by a body spray-spritzing villainess who hates how they smell? Maybe they were actually million-dollar mice, stolen by crime bosses for their high value. Unless they mutated, developed superpowers, and escaped on their own . . . Mice don't just disappear, right? Crack open a What Happened? book to investigate a preposterous mystery from four different perspectives. See what the witnesses get right . . . and what they get hilariously wrong. Bet you'll never guess what really happened!