When the planet Mongo breaks out of its orbit and imperils Earth, Flash Gordon (Buster Crabbe) teams with Dr. Zarkov to save the day. After landing on Mongo, Flash, Zarkov (Frank Shannon) and Flash's girlfriend, Dale (Jean Rogers), are taken to Mongo's ruler: Ming the Merciless (Charles Middleton).
With help from Ming's daughter, Flash gets down to the business of stopping Ming and saving Earth.
A totally addictive sci-fi serial from 1936 starring Buster Crabbe. In the 1930s future, rocket ships can be controlled using only two switches and a dial. Go figure.