John Carter

In 1881, Edgar Rice Burroughs arrives at the estate of his recently deceased uncle, John Carter, a former American Civil War Confederate Army captain. Per Carter's instructions, the body is put in a tomb that can be unlocked only from the inside. His attorney gives Carter's journal to Burroughs, to whom Carter bequeathed his fortune.
In a flashback to 1868 in the Arizona Territory, Union Colonel Powell arrests Carter with hopes that he will help in fighting local Apache. Carter escapes his holding cell with cavalry soldiers in close pursuit. After a run-in with a band of Apaches, Carter and a wounded Powell hide in a cave that is filled with gold. A mysterious man, later revealed to be a Thern, appears in the cave and attacks them with a knife; Carter kills him but accidentally activates the Thern's medallion and is transported to a ruined and dying planet, Barsoom, known to Carter as Mars. Because of his different bone density and the planet's lower gravity, Carter can jump high and perform feats of incredible strength. He is captured by the Tharks, a nomadic tribe of Green Martians and their Jeddak, Tars Tarkas.
Elsewhere on Barsoom, the Red Martian cities of Helium and Zodanga have been at war for a thousand years. Sab Than, Jeddak of Zodanga, armed with a weapon obtained from the Thern leader Matai Shang, proposes a cease-fire and an end to the war by marrying the Princess of Helium, Dejah Thoris. The Princess escapes and is rescued by Carter.
Carter, Dejah, and Tarkas's daughter, Sola, reach a spot in a sacred river to find a way for Carter to get back to Earth. They discover that the medallions are powered by a "ninth ray" that is also the source of Sab Than's weapon. They are then attacked by a vicious race called the Warhoon under the direction of Shang. Carter and Dejah are taken back to Zodanga. Dejah grudgingly agrees to marry Sab Than and gives Carter instructions on how to use the medallion to return to Earth. Carter decides to stay but is captured by Shang, who explains how Therns manipulate the civilizations of different worlds to their doom, feeding off the planet's resources in the process, and intend to do the same thing with Barsoom by choosing Sab Than to rule the planet. Carter escapes and returns to the Tharks with Sola to request their help. There they discover that a brute, Tal Hajus, has overthrown Tarkas. Carter and an injured Tarkas battle with two enormous Great White-Apes in an arena before Carter kills Hajus, thereby becoming the leader of the Tharks.
The Thark army storms Zodanga, but it is empty; realizing that their army is waiting outside Helium, Carter and the Tharks commandeer the Zodangan airships and fly to Helium. Carter defeats the Zodangan army, while Sab Than is killed and Shang escapes. Carter becomes prince of Helium by marrying Dejah. On their first night, Carter decides to stay on Mars and throws away his medallion. Seizing the opportunity, Shang reappears and gives Carter another challenge by sending him back to Earth. Carter embarks on a long quest to find one of the Therns' medallions on Earth; after several years, he appears to die suddenly and asks for unusual funeral arrangements — consistent with his having found a medallion, since his return to Mars would leave his Earth body in a coma-like state, and makes Burroughs his protector.
Back in the present, Burroughs runs back to Carter's tomb and uses clues to open it. Just as he does, a Thern appears and raises a weapon before Carter appears and shoots the Thern dead. He reveals that he had never found another medallion; instead, he devised a scheme to lure a Thern from hiding, thus winning Shang's challenge. Carter then uses the dead Thern's medallion to return to Barsoom.