Join Og and his little sister Bop on a fun-filled adventure in this adorable, rhyming Pre-Level 1 Ready-to-Read by award-winning and New York Times bestselling author Ame Dyckman and renowned illustrator Elio! Monster Og and his little sister Bop are excited to play outside. But when Bop finds a balloon, it lifts her high into the sky! Can Og come up with a plan to rescue Bop?