On a beach, a teenaged boy called Lewis has found some treasure, only to spot a monster rising behind him. The Doctor grabs Lewis and the two head for higher ground. The Doctor tells Lewis that the monster is Sea-Rah. As the two climb, he explains that the mace Sea-Rah is carrying should contain The Gemstone of Isop, but it fell through a hole in time and ended up on Earth. Sea-Rah is going mad until he finds it again. The treasure that Lewis found on the beach is actually The Gemstone of Isop.