Burroughs imagines a future two centuries onward in which that view prevailed and the Western Hemisphere severed contact with the rest of the world.

Consequently, the Eastern Hemisphere has exhausted itself in war and Europe has descended into barbarism while the Americas, sheltered from the destruction, have continued to advance and joined peacefully into the union of Pan-America.

In 2137, Pan-American Navy Lieutenant Jefferson Turck is commander of the aero-submarine Coldwater, tasked with patrolling the 30th meridian from Iceland to the Azores.

While the crew attempts repairs Turck and three subordinates, Snider, Taylor and Delcarte, go fishing in a small boat to reprovision the vessel.

Soon after, Turck and Victory fall separately into the hands of soldiers of the Abyssinian Empire, a black super-state now ruling all of Africa, most of Europe, and the Arabian Peninsula.

Turck's master takes him to New Gondar, built on the site of ancient Berlin, where the Abyssinian Emperor, Menelek XIV, holds court.

Taylor and Delcarte are found, communications between the hemispheres are re-opened, and diplomatic relations established between Pan-America and China, with commerce to follow.