From a real explorer's hat that takes him through dark caves ... to the striped engineer's cap he wears to drive a train ... and the hard hat that's handy when he's welding a girder, Martin dashes, hat by hat, through a grand round of adventures. Martin's curiosity about the world is every child's, and his magnificent accomplishments every child's to enjoy. The authors take a young boy on a wonderfully imaginative journey and bring him back home for bedtime.