Passed | | Action, Adventure
Hank Davis, foreman on a huge dam project, enlists the aid of his two flyer friends when a sinister figure known as The Black Ace leads his Mystery Squadron of masked pilots in an attempt to destroy the dam.
It is possible that the man portraying the Black Ace in full costume is not Jack Mulhall but actually a stuntman.
Good guys Bill and Davis are apparently clubbed unconscious by an unseen hand while exploring the Mystery Squadron's secret cave. Initially Davis lies to the right of Bill, but later he's seen laying on the left.