Major Ben McBride was a childhood friend of Bowen Tyler's. The last McBride heard of Tyler, he had disappeared when his ship sank en route from the United States to Europe, in 1916. One year later in 1917, a message in a bottle was found by a Scottish lighthouse keeper, detailing a fantastic story about the lost continent of Caprona, and Tyler's adventures there.
The message we given to McBride, who wanted to mount a rescue operation right away. Unfortunately, America entered the Great War not long after this, and McBride was sent to Europe to fight against the Germans. During this time, he attained the rank of major and met and befriended another soldier, Hogan, who saved his life. After the War, the retired Major McBride brought Tyler's message to a noted paleontologist, Edwin Norfolk, and asked him to authenticate some specimens Tyler had included in the bottle. Norfolk did, causing a stir around the world.
With the assistance of Captain Lawton, McBride, armed with money provided by a London newspaper owned by Charlotte Cunningham's father, journeyed to the Arctic aboard the Polar Queen. Once there, leaving Lawton in command of he waiting Polar Queen, McBride flew in a plane over the ice cliffs, accompanied by Dr. Norfolk, Charlotte and his old war buddy Hogan. Their plane crashed after an encounter with a pterodactyl, forcing McBride's party to head further inland on foot. Hogan was left behind to fix the plane.
McBride and his team encountered Band-Lu cavemen, dinosaurs and eventually an English-speaking Gah-Lu woman named Ajor, who claimed to know Tyler. Not long after they were met by Naga soldiers, led by Chung-Sha, who also spoke English and claimed to know Tyler's wherabouts. Despite Ajor's warnings that the Nagas were evil, McBride and his party went with Chung-Sha to the Mountain of Skulls. Here, they brought before the Nagas' ruler Sabbala, who had McBride and Dr. Norfolk thrown into the dungeons while he prepared to sacrifice Charlotte and Ajor to the Nagas' volcano god.
In the dungeons, McBride and Norfolk met Tyler, and the two childhood friends were reunited at last, as Tyler told the sad tale of how Sabbala had massacred the Gah-Lu and killed Lisa. Spurned by a desire for revenge as well as to save the girls, the three men overpowered the guards and escaped, stopped Sabbala from sacrificing Charlotte and Ajor, and escaped from the Naga city. Chung-Sha and his men pursued, and McBride soon found himself in a duel with the Naga guard commander. A duel he almost lost, but Tyler came to his rescue and slew Chung-Sha - at the cost of his own life.
The dying Tyler urged McBride and the others to escape Caprona while they could, and a mournful McBride along with Norfolk and Charlotte made it back to the plane where Hogan had finished the repairs. They escaped back to the Polar Queen before a volcanic eruption destroyed Caprona's northern regions.