Celebrate Valentine's Day with Rocket, the canine star of Tad Hills's New York Times bestselling picture books, in this new adventure! Someone is leaving friendly notes for Rocket. . . . It must be a secret valentine! But who could it be? Join Rocket, Bella, and Owl as they look for clues, follow the notes, and try to solve the mystery! Each "note" contains a rhyming stanza with the last word missing, inviting readers to join in the fun, guess the answer, and help Rocket get one step closer to finding his secret valentine.