The plot is ridiculously far-fetched but in a serial that’s really a feature rather than a bug. Stephen Gray is a contractor building a dam but the project is being sabotaged by aerial attacks by a group of pilots known as the Mystery Squadron. These rogue flyers are led by a mysterious masked figure, the Black Ace. They have half a dozen aircraft equipped with flame-throwers. If you were going to arm aircraft for these kinds of sabotage operations I would have thought there were much simpler and more effective ways of doing so than fitting a rather clumsy flame-throwing device at the tail but one of the requirements of a serial is goofy gadgetry and the flame-throwers do look reasonably impressive.
Mr Gray decides he needs protection so he hires a couple of barnstorming aviators, Fred Cromwell (Bob Steele) and Bill Cook (Guinn 'Big Boy' Williams). Their efforts to discover the base from which the Mystery Squadron is operating and the identity of the Black Ace provide plenty of opportunities for various good guys to get captured by the bad guys and for various bad guys to get captured by the good guys. Those kinds of plot twists were pretty well essential in order to spin out a serial for a dozen or so episodes (this one runs for twelve episodes).
Naturally Stephen Gray has a beautiful high-spirited daughter, Dorothy, who also happens to be a pilot. Needless to say she will need to be rescued on various occasions.
As for the identity of the Black Ace there are several possible suspects and the mystery is sustained fairly well. There’s a sub-plot involving a gold mine, always a popular concept in a serial.
Much of the action takes place at the San Juan Tavern, a large establishment well equipped with secret passageways and hidden staircases. There will be endless chases through these secret passageways.
The big drawcard though is the promise of aerial action and on that score this serial certainly delivers the goods. There’s at least one flying sequence (and often more) in each episode. The aerial sequences are quite impressive with some suitably hair-raising stunt flying. The Mystery Squadron’s base is in a cave concealed in a canyon, which seems like the sort of location for a base that would practically guarantee you would lose most of your aircraft in accidents in the first week. It might not be a very sensible location but it looks good. There’s a considerable reliance on miniatures for the many scenes of aircraft being blown up and the miniatures work is very proficient for a low-budget production.
Serials often relied too much on recycling footage by means of flashbacks in order to pad them out to the required number of episodes. The Mystery Squadron uses this technique but does so sparingly.
The acting is of the standard you expect in a serial, in other words it’s mostly wooden and the dialogue (which isn’t exactly sparkling to begin with) is delivered in a generally stilted manner. That doesn’t matter too much in a serial. What matters is that the heroes should look heroic, the villains should talk like villains and the heroine should be beautiful and high-spirited. The Mystery Squadron satisfies these requirements. Bill Cook’s addiction to jelly beans provides a running gag that gets a little tired after a while but Guinn 'Big Boy' Williams is there to provide some comic relief which he does without being too irritating.
Pacing is always a potential problem in a serial but this one moves along pretty swiftly. The action comes thick and fast and the episode cliffhangers are done well. Mascot had vast experience in turning out serials that provided good entertainment on modest budgets and they knew how to work the serial formula to good effect.
The Mystery Squadron is available on DVD from Alpha Video, a company renowned for spectacularly horrible transfers of public domain movies. Even by their standards this one is atrocious. On the other hand you can pick it up for a couple of dollars and that eases the pain a little.
The Mystery Squadron offers plenty of thrills and serial fans should get a great deal of enjoyment out of this one. While the DVD is terrible it is absurdly cheap and the serial itself can be highly recommended.