To avenge his father, Stanley Stanfield (Onslow Stevens) allies himself with Prof. Carl Van Dorn, a 'genius with electricity' who brings an invisibility belt, a death-ray, and a giant remote-control robot to the struggle. Together with spunky girl-reporter Gloria Grant (Ada Ince), the daughter of Wade Barnett (Walter Miller), the merciless businessman who drove Stanfield's father to death, they take on Barnett's crew of heavies, led by tough-guy Dorgon (Richard Cramer) for 12 chapters packed with brawls, explosions, booby-traps, car-wrecks, plane crashes and burning ships (without any of the men displacing their fedoras). The serial is quite well made and the plot, while admittedly far-fetched, holds together well and the cliff-hanger endings (and their subsequent resolutions), although 'typical' of the genre, are satisfying (ie no 'cheats'). Unusual for the genre, the plethora of fantastic gadgets are not in the hands of a criminal mastermind, but rather in those of an ally of the hero, and the blood-thirsty professor, who is just itching to turn his death ray on something other than plants, is easily the most entertaining character in the serial. The special effects are quite good (for era and genre). The 'turning invisible' effects are very well done and, unlike cheaper chapterplays (such as 'The Purple Monster Strikes'), there is not a constant recycling of optical effects as numerous characters use the 'ray' to turn invisible in a variety of places and poses. There is efficient use of stop-motion to demonstrate the effects of the death ray on living tissue and the robot is great: a giant flailing tin-man with orangutan-like arms and a huge nose that terrifies even the coolest of the heavies. Not unusual for a 12-parter, the episodes become a bit repetitive (Stanley gets tied up a lot and there is always someone eavesdropping when an important plot-point is discussed) but the story moves along briskly to an agreeable conclusion. Cinematographically, the 90-year-old serial has aged well except for some Hal Roach-like undercranking in the fight scenes that results in unintentionally humorous sped-up effects. Note: Roy Kinnard's 2008 book 'Science Fiction Serials: A Critical Filmography of the 31 Hard SF Cliffhangers' states that this serial has been lost but recently high-quality copies of all 12 chapters have appeared on You-tube.
