From New York Times bestselling and award-winning author-illustrator Mark Teague comes a hilarious whodunit picture book about something suspicious afoot on Old MacDonald's farm! Something mysterious--and silly!--is up at Old MacDonald's farm. Thank goodness Officer Busby is on the case, because, as she says, "Whoever did this knew their business." Silly business, that is. What could possibly be going on? Well, it's April 1st. And everyone knows what that means...