A man known only as Robur shoots down and takes aboard his
airship, Prudent, his daughter Dorothy, her fiancé Evans, all of whom were exploring a
mountain crater in their powered
balloon, along with
US government agent Strock, who had hired them to look for signs of
volcanic activity. The supposed eruption was caused by Robur working on his airship,
the Albatross; he had also inadvertently broadcast a biblical passage over a voice amplifier, stirring religious fears among the citizenry of the nearby town. Robur has been traversing the globe in his airship with the obsessive aim of enforcing peace on the world by virtue of his superior military capabilities. He has a loyal crew of like-minded, equally fanatical
idealists. The captives learn how his ship operates, and about his technical advances, including generation of
electrical power by crossing "lines of magnetic force", a quaint but accurate description of a dynamo's operating principle. The prisoners are anxious to escape, but don't fully trust Strock, who appears at times to side with Robur. After saving Evans' life, Strock explains that his oath of loyalty to Robur was insincere, and that as a captive he feels no compunction to behave as a gentleman. Robur proceeds to destroy various nations' means of making war, but a
desert conflict wounds Robur and damages the
Albatross. After the airship succeeds in escaping and Robur recovers, the ship anchors at an
island for repairs, where the captives rig the armoury with an explosive charge. All escape down the anchor line except Strock, who follows while being shot at by the crew. First Strock, then Evans, work at cutting the anchor line, finally releasing the airship, which is damaged beyond repair moments later when the
gunpowder explodes. Robur orders his crew to abandon ship, but they choose to ignore his final order, and gather in his quarters while he reads from
Isaiah 2:4 (the "
swords into plowshares" passage), reminding them of their pledge to try to rid the world of war. The ship, along with Robur and his crew, crashes into the ocean and explodes, while the captives watch, injured but alive, from the shore. ==Cast==