When Kate is given a colossal steam train, the Silver Arrow, for her birthday, she can't believe her luck. After eleven years of waiting, adventure has finally found her! Soon the Silver Arrow is whisking Kate and her brother Tom to a magical station where their passengers stand ready to board. From the porcupine to the pangolin, each one is rare and wonderful. But these animals have been waiting a very long time too. Can Kate deliver them home ... before it's too late?