After returning from Wonderland, Celia and Tyrus journey to the Looking-Glass World to reclaim their mirror images and stop a war between two powerful queens. When the Bandersnatch steals one of Lewis Carroll's lost diaries, Celia and Tyrus try to get it back, only to tumble through a magic mirror into the Looking-Glass World, a place where everything—themselves included—is divided in two. Celia's logic and Tyrus's imagination now belong to their mirror images, Lia and Ty. Left without their greatest problem-solving skills, Celia and Tyrus must rely on each other as they play a massive game of chess to try to catch their mirror images. Along the way, they engage in a rhyming battle with Tweedle Dee and Tweedle Dum, seek advice from Humpty and Dumpty, and learn how to believe in the impossible from the White Queen, who remembers the future as if it were the past. As the final battle draws near, Celia and Tyrus form an uneasy alliance with Lia and Ty to find the legendary vorpal sword—the only weapon powerful enough to stop the war. If they fail, not only will two kingdoms be destroyed, but Celia and Tyrus might never regain their stolen talents and could be trapped in the Looking-Glass World forever.