Synopsis: A volcanic eruption in the North Atlantic brings to the surface a 65-foot pre historic monster. Two treasure divers capture the creature and take him to London where he is put on display in a circus. A scientist is thoughtful enough to point out that the sailor's bonanza is only an infant and that a full grown specimen would be over 200 feet in height. Sure enough, Gorgo's mama comes thundering ashore, reclaims her offspring and heads back to sea -- but not before she trashes a generous portion of London.