With a shipwreck, the Robinson family becomes castaways on a lush tropical island. While the mother (Dorothy McGuire) isn't too happy about this fact, the father (John Mills) and the sons (James MacArthur, Tommy Kirk, Kevin Corcoran) are thrilled at the prospect of carving out a new life for themselves. Later on, the little party is joined by Janet Munro, the daughter of a sea captain who has been captured by a band of pirates...