Plot
In the late Victorian period, two cousins, nine-year-old Richard and seven-year-old Emmeline Lestrange, and galley cook Paddy Button, are shipwrecked on a lush tropical island in the South Pacific. Paddy cares for the children and forbids them "by law" from going to the other side of the island, where he finds an altar with bloody remains from human sacrifices. He also warns them against eating any deadly scarlet berries. He dies after a drunken binge, and the children rebuild their home on a different part of the island.
Having reached puberty, the two go skinny dipping in the ocean, but Emmeline is uncomfortable with her sexual attraction to Richard and declines to share her "funny" thoughts with him. She is frightened by her first menstrual period and refuses to allow Richard to inspect her for what he imagines is a wound.
Eventually, Richard recognizes his attraction to Emmeline. She ventures to the forbidden side of the island and sees the altar. Associating the blood with Christ's crucifixion, she concludes that the altar is God and tries to persuade Richard to go to the other side of the island to pray with her. Richard is shocked at the idea of breaking the law and they argue. When Richard tries to initiate sexual contact with Emmeline, she rebuffs him. He hides from her and masturbates.
When a ship appears for the first time in years, Emmeline does not light the signal fire and the ship passes by without noticing them. When Richard confronts Emmeline about her failure, she asserts to his angry disbelief that the island is now their home and that they should remain there. Emmeline also reveals that she knows about Richard's masturbation and threatens to tell her Uncle Arthur about this. They fight and she throws a coconut at him, hitting him in the head by chance. Richard angrily slaps her and kicks her out of their shelter.
Emmeline steps on a venomous stonefish. Weak from the poison, she pleads with Richard to "take [her] to God". Richard carries her across the island and places her on the altar. Emmeline recovers and they swim naked in the lagoon. Noticing their bodies' reactions, they discover sexual intercourse and become lovers. Neither recognizes what is happening when Emmeline becomes pregnant, and they are stunned to feel the baby move inside her abdomen, assuming her stomach is causing the movements.
Months later, Richard observes indigenous people performing a human sacrifice in front of the statue. He becomes frightened and runs away to find Emmeline, whom he finds in labor. Emmeline gives birth to a baby boy, whom they name Paddy.
A ship led by Richard's father, Arthur, approaches the island and sees the family playing on the shore. Content with their lives, Richard and Emmeline walk away instead of signaling for help. Arthur assumes the mud-covered couple are not Richard and Emmeline.
Visiting their original homesite, Richard searches for bananas while Paddy, unnoticed, brings a branch of poisonous Abrus precatorius seeds into the boat with Emmeline. Paddy tosses an oar out of the boat as it drifts from the shore. Richard swims after them followed closely by a shark. Emmeline throws the other oar at the shark, striking it and giving Richard time to get into the boat. The boat drifts oarless out to sea.
After drifting for days, Richard and Emmeline wake up to find Paddy eating the Abrus precatorius seeds. Hopeless, Richard and Emmeline eat the seeds as well, and lie down to await death. Some hours later, Arthur's ship finds them. Arthur asks, "Are they dead?" The officer assures him, "No, sir. They're asleep."
