A Princess of Mars recap

After an encounter in an Arizona cave, Civil War veteran John Carter is inexplicably transported to Barsoom, a drying world whose lower gravity gives him exceptional strength. Captured by the nomadic green Martian Tharks, he befriends Sola, Woola, and the warrior Tars Tarkas. He also meets Dejah Thoris, a red Martian princess of Helium, and falls in love with her. Carter escapes captivity, survives imprisonment by the Warhoons, and reaches Zodanga, whose prince intends to force Dejah into marriage while Zodanga attacks Helium. With Tars Tarkas and a green Martian army, Carter takes Zodanga, rescues Dejah, and helps Helium win the war. Tars becomes jeddak of the Tharks, and Carter and Dejah marry. Years later Barsoom's atmosphere machinery stops. Carter enters the plant and restarts it, then wakes on Earth before seeing the result. After ten years he still does not know whether Barsoom or his family survived.

John Carter, a Virginia veteran prospecting in Arizona after the Civil War, follows his partner James Powell when danger threatens their claim. Powell is killed, and Carter takes refuge in a cave while pursued. He then undergoes an unexplained separation from his body and finds himself on a strange, arid world. The planet's lower gravity gives him extraordinary jumping ability and strength. He encounters towering, four-armed green people, later known to him as the Tharks, and is taken to their deserted city. Unable to speak their language and uncertain of their intentions, Carter nevertheless earns wary respect by defending himself. Tars Tarkas emerges as a leading warrior among his captors, while Sola is assigned to watch and teach him. Woola, the fierce calot set to guard him, becomes attached to Carter after receiving kindness rather than punishment.

Carter learns the Tharks' language and observes a society organized around warfare, communal child-rearing, and the public rejection of private affection. Sola's sympathy and Sarkoja's cruelty reveal that individuals do not all conform equally to those customs. A Thark force captures a small aircraft and its passenger, Dejah Thoris, a red Martian princess of Helium. She had been taking part in scientific work related to the planet's dwindling resources. Carter intervenes when she is threatened and becomes her champion, though their different customs repeatedly cause misunderstanding. His victories in combat raise his position among the Tharks and bring him closer to Tars Tarkas, while the authority of the cruel jeddak Tal Hajus remains a danger to them all.

Carter and Dejah grow close, but he misunderstands the significance of Barsoomian courtship and fails to give the response she expects. Sola privately explains that she is Tars Tarkas's daughter and that Sarkoja caused the death of her mother; Tars has concealed his paternal love because Thark society condemns such bonds. Carter, Dejah, Sola, and Woola plan an escape toward Helium. Their attempt is disrupted, and Carter is captured by Warhoons, another green Martian people, while the others' fate remains uncertain. His growing loyalty is now divided between finding Dejah and helping Tars challenge the customs and leadership that have made compassion dangerous among the Tharks.

Held by the Warhoons, Carter is forced into arena combat and survives with the aid of Kantos Kan, a red Martian officer of Helium. After escaping, Carter reaches the isolated atmosphere plant whose machinery sustains breathable air across the planet. Its keeper admits him after telepathically giving him the knowledge needed to open the entrance in an emergency. Carter then travels toward Zodanga and disguises himself as an air scout. He learns that Zodanga is pressing its war against Helium and that Dejah is again in danger. Kantos Kan and other Heliumite allies help him move within the enemy city while he searches for her.

In Zodanga, Carter finds Dejah and learns that she has agreed to marry Prince Sab Than to spare Helium from further destruction. Carter reveals that he loves her, clearing the misunderstanding between them, and promises to stop the marriage. He escapes the city and reunites with Tars Tarkas, Sola, and Woola. Tars has accepted the truth about Sola and now openly stands with his daughter and Carter. Together they rally green Martian warriors against Tal Hajus and in support of Helium. The alliance attacks Zodanga, giving Carter a chance to reach Dejah before the political marriage can be completed.

Carter and his allies seize Zodanga, prevent Dejah's marriage to Sab Than, and help the forces of Helium defeat their enemy. Tars Tarkas publicly confronts and kills Tal Hajus, becoming jeddak of the Tharks and reshaping their relationship with the red Martian cities. Carter and Dejah marry and live together for nine years. When the atmosphere plant suddenly stops and the air begins to fail, Carter uses the keeper's telepathic secret to enter the otherwise sealed facility. He succeeds in starting the machinery but collapses before he can see the outcome. He awakens back in the Arizona cave, in the body he left there. Ten years pass on Earth. Carter can see Mars in the night sky, but he receives no answer and does not know whether Dejah, their unborn child, or Barsoom survived the crisis.

Carter and his allies seize Zodanga, prevent Dejah Thoris's forced marriage to Sab Than, and help Helium defeat its enemy. Tars Tarkas exposes Tal Hajus's cruelty, kills him in single combat, and becomes jeddak of the Tharks. The green Martian alliance with Helium is confirmed, and Carter marries Dejah. Nine years later, with Dejah expecting their child, the machinery that maintains Barsoom's atmosphere fails. Carter reaches the sealed atmosphere plant by using the telepathic knowledge entrusted to him and starts the machinery, but loses consciousness before he can learn whether the planet is saved. He wakes in his physical body in the Arizona cave. Ten years pass on Earth without any sign from Barsoom, leaving him uncertain whether Dejah, their child, or the planet survived.