The story opens in the royal gardens of Ptarth, where Thuvia rejects the aggressive advances of Astok, Prince of Dusar. Carthoris, son of John Carter, defends her honour, inadvertently setting off a chain of political conspiracies designed to plunge Helium, Ptarth, and Kaol into bloody warfare. Shortly after this encounter, Thuvia is abducted from her father's court by Dusarian agents wearing Heliumitic insignia, casting immediate suspicion upon Carthoris. Determined to clear his name and rescue the woman he loves, Carthoris launches an unauthorized flight that leads him far across the red planet's dead sea-bottoms to the mysterious, ruined city of Aaanthor.
Following the trail of her abductors, Carthoris encounters the ferocious green warriors of Torquas and survives incredible perils in the desert wilderness. Meanwhile, Thuvia is dragged through various strongholds before she stumbles upon Lothar, a forgotten city inhabited by ghostly illusions and a dwindling race of etherealists and realists. Here she meets Tario, the strange ruler of Lothar, and Jav, whose mental projections conjure phantom armies of bowmen that wage silent, deadly wars against the besieging Torquasian hordes. Carthoris eventually penetrates this hidden valley, only to find himself entangled in the bizarre psychological conflicts of the Lotharians while attempting to secure Thuvia's freedom.
As the narrative expands, political tensions reach a boiling point across Barsoom. Powerful armadas from Dusar, Ptarth, and Kaol mobilize for a decisive naval conflict, while hidden spies manipulate state secrets to ensure mutual destruction. Astok struggles to dispose of his captive as his father, the cruel Jeddak of Dusar, demands her execution to protect their nation's guilt. Thuvia remains steadfastly defiant, refusing both Astok's advances and the grim fate prepared for her in the high towers of Dusar.
Carthoris, aided by loyal allies such as Kar Komak, the ancient bowman of Lothar, navigates enemy territory disguised as a panthan. He infiltrates Dusarian strongholds and discovers the true plot behind Thuvia's imprisonment. Following a daring rescue from the very jaws of execution, the protagonists find themselves caught between pursuing enemies and the vast battlefields where the fate of empires hangs in the balance.
The climax brings the characters into contact with Kulan Tith, Jeddak of Kaol, whose warfleet has been decimated by green hordes on the arid plains. Carthoris orchestrates a daring rescue that overcomes seemingly impossible odds, demonstrating unmatched valour and chivalry. Ultimately, Kulan Tith recognizes the true depth of affection between Thuvia and the Heliumite prince, choosing nobility over possessiveness and setting the stage for a lasting peace across the troubled globe of Barsoom.
