"A brand-new series by Ron Roy, spun off from A to Z Mysteries! It's a Valentine's Day party! Bradley is passing out his class's valentines, but one of them has no name on it. Inside, the card tells the class to look in the closet. When they open the closet door, the kids find a rabbit named Douglas in a cage! What mysterious friend left him there? And why? Then the bunny gets sick. It's up to Bradley, Brian, Lucy, and Nate to track down his owner and figure out what is wrong with poor little Douglas."