Twenty Thousand Leagues Under the Sea recap

Naturalist Pierre Aronnax joins the frigate Abraham Lincoln in pursuit of a supposed sea monster, accompanied by Conseil and harpooner Ned Land. The object is actually the Nautilus, an advanced submarine commanded by the enigmatic Nemo. Taken aboard and forbidden to leave, the three cross the oceans while Aronnax studies an unprecedented marine world. They walk on the seabed, visit coral forests and ruins, pass through a hidden route beneath Suez, see Nemo aid a pearl diver, and reach the South Pole under the ice. Ned repeatedly seeks escape, while Aronnax's fascination delays him. Nemo's compassion toward the oppressed contrasts with secrecy, grief, and a deliberate attack that sinks a warship. Aronnax, Conseil, and Ned finally flee in the submarine's boat as the Nautilus enters a Norwegian whirlpool. They are rescued, but the fate of Nemo and his vessel remains unknown.

Ships across the world's oceans report encounters with a fast, luminous object, and several vessels are damaged. Opinion settles on the possibility of an enormous narwhal. French naturalist Pierre Aronnax, returning from scientific work with his servant Conseil, accepts an invitation to join the United States frigate Abraham Lincoln in hunting it. The expedition is commanded by Farragut and includes Ned Land, a celebrated Canadian harpooner who doubts that any animal could do such damage. After months of searching, the crew sights a powerful object in the Pacific and attacks. Its surface proves resistant to cannon and harpoon. The collision throws Aronnax into the sea; Conseil follows him, and the two are later joined by Ned. They take refuge on the smooth metal back of the supposed creature and realize that it is an artificial vessel just before its crew takes them inside.

Held in a dark compartment, Aronnax, Conseil, and Ned meet the vessel's commander, who calls himself Nemo. He explains that the Nautilus is an electrically powered submarine built to live independently of land. His libraries, art, food, clothing, and energy all come from the sea or from resources gathered beneath it. Nemo has abandoned national society and will not reveal his origins. Because the prisoners now know the Nautilus exists, he refuses ever to release them, though they may move freely aboard except when temporarily confined for reasons he will not explain. Aronnax is fascinated by the engineering and scientific opportunities. Ned considers permanent captivity intolerable, while Conseil follows his master. The Nautilus begins a long passage through the Pacific, and Aronnax learns its design, power, navigation, and extraordinary range.

Nemo invites the captives on a walk in diving suits through an underwater forest, where they travel across the seabed among unfamiliar plants and animals. Continuing west, the Nautilus visits islands associated with earlier voyages and then strikes a reef in Torres Strait. While the tide is low, Aronnax, Conseil, and Ned receive permission to go ashore for food. Local islanders pursue them back to the stranded submarine, but Nemo remains confident: when the tide frees the vessel, an electrical defense prevents boarding without killing the attackers. Soon afterward Nemo abruptly seals the prisoners in their quarters. When released, Aronnax is asked to treat a crewman who has suffered a fatal head injury. The next day Nemo leads a funeral procession through the sea and buries the sailor in a coral cemetery, beyond the reach of the land world Nemo has rejected.

Crossing the Indian Ocean, Nemo takes Aronnax, Conseil, and Ned to a pearl fishery before its season opens. They see an impoverished diver attacked by a shark. Nemo intervenes with a knife, Ned kills the animal with his harpoon, and Nemo secretly gives the rescued man a bag of pearls. The Nautilus enters the Red Sea and passes into the Mediterranean through an underwater tunnel beneath Suez that Nemo discovered. Near the Greek islands, Aronnax observes signs that Nemo is sending gold to people engaged in resistance on land, though the captain gives no full explanation. The vessel races through the Mediterranean, limiting Ned's chance to escape, and reaches Vigo Bay. There Nemo gathers treasure from Spanish ships sunk centuries earlier and rejects the idea that he lacks means to support causes he chooses. The Nautilus then crosses the Atlantic to submerged ruins that Nemo identifies as Atlantis.

The Nautilus replenishes its fuel at an undersea coal deposit inside an extinct volcanic chamber, then crosses the Sargasso Sea. Nemo's crew kills attacking sperm whales in a violent hunt while leaving the nonaggressive whales they threatened unharmed. The submarine turns south and forces a route through Antarctic ice. Nemo and his companions reach open water near the pole, go ashore, and claim the site before winter darkness closes in. On the return journey, shifting ice traps the Nautilus beneath the surface. The crew cuts desperately through the barrier while the air becomes unbreathable. Aronnax nearly suffocates, but Conseil and Ned share the last air from their diving equipment with him. The Nautilus finally breaks through and renews its atmosphere. The three captives survive, yet Ned's wish to escape is now stronger, and even Aronnax's scientific enthusiasm is strained by the risks of remaining aboard.

Heading north through the Atlantic, the Nautilus encounters giant squid. The crew fights them at the surface, and one sailor is dragged away despite Nemo's attempt to save him. Nemo withdraws further into grief. Later a warship pursues and fires on the submarine. Nemo refuses to identify it, orders an attack, and deliberately rams and sinks it while Aronnax watches. In Nemo's room, Aronnax sees him mourning before portraits of a woman and children, but the history behind his vengeance remains unstated. Aronnax can no longer balance the voyage's scientific value against captivity and destruction. He, Conseil, and Ned attempt escape in the Nautilus's detachable boat near Norway. At that moment the submarine is drawn into the Moskenstraumen whirlpool. Aronnax is knocked unconscious and later awakens with his companions among fishermen on the Lofoten Islands. All three have escaped alive, but they cannot say whether Nemo or the Nautilus survived. Aronnax returns to record what he witnessed, leaving the captain's identity and fate unresolved.

After the polar ordeal, Nemo becomes increasingly withdrawn and the Nautilus turns north through the Atlantic. The crew fights giant squid, losing one sailor, and Nemo later uses the submarine to destroy a pursuing warship. Aronnax sees that the attack is deliberate and connected to Nemo's still-unexplained history; the captain mourns before portraits of his lost family. Horrified and unable to justify remaining for scientific discovery, Aronnax agrees to Ned's escape plan. As the three prisoners launch the Nautilus's boat near Norway, the submarine is caught in the Moskenstraumen whirlpool. Aronnax loses consciousness and awakens with Conseil and Ned in the care of fishermen on the Lofoten Islands. They survive, but do not know whether the Nautilus and its crew escaped the vortex. Aronnax returns able to publish the record of their undersea journey, while Nemo's identity, ultimate fate, and moral reckoning remain unresolved within this book.