Atlanna (Nicole Kidman), the queen of the underwater kingdom of Atlantis, washes up on the shores of Amnesty Bay, Massachusetts. She's rescued by lighthouse keeper Tom Curry (Temuera Morrison) and they fall in love. They have a son and live a happy and uneventful life, until Atlantis soldiers attack the lighthouse when they're ordered to bring Atlanna back home. To keep her family safe, Atlanna complies.

Years later, Arthur (Jason Momoa) discovers he's the heir to the Atlantis throne and is to be crowned King of the Seven Seas. However, his younger half-brother Orm (Patrick Wilson) wants the crown for himself.

Country girl Gabrielle (Keira Knightley) marries an author, known simply as "Willy" (Dominic West). Willy is famous for his writing, but as Gabrielle soon learns, he puts his name on other people's work. When he asks Gabrielle to write novels to be published under his name, she dutifully writes a book called Claudine a l'ecole, based her school days. It becomes an instant success, flying off the shelves like no other book attributed to her husband. The novel is so popular that it spawns a number of products.

However, as her husband gets all the glory, Gabrielle, who has changed her name to Colette, slowly comes to the realization that this doesn't sit well with her. Willy demands that she write more Claudine novels, and she does, to please him and more importantly, to make money to pay for Willy's lavish lifestyle, which includes constant gambling and whoring. Finally tired of Willy's demands and philandering, Colette discovers she is attracted to women and has affairs of her own.