In 1996, treasure hunter Brock Lovett and his team aboard the research vessel Akademik Mstislav Keldysh search the wreck of RMS Titanic for a necklace with a rare diamond, the Heart of the Ocean. They recover a safe containing a drawing of a young woman wearing only the necklace dated April 14, 1912, the day the ship struck the iceberg.[Note 1] Rose Dawson Calvert, the woman in the drawing, is brought aboard Keldysh and tells Lovett of her experiences aboard Titanic.
In 1912 Southampton, 17-year-old first-class passenger Rose DeWitt Bukater, her fiancé Cal Hockley, and her mother Ruth board the luxurious Titanic. Ruth emphasizes that Rose’s marriage will resolve their family’s financial problems and retain their high-class persona. Distraught over the engagement, Rose considers suicide by jumping from the stern; Jack Dawson, a penniless artist, intervenes and discourages her. Discovered with Jack, Rose tells a concerned Cal that she was peering over the edge and Jack saved her from falling. When Cal becomes indifferent, she suggests to him that Jack deserves a reward. He invites Jack to dine with them in first class the following night. Jack and Rose develop a tentative friendship, despite Cal and Ruth being wary of him. Following dinner, Rose secretly joins Jack at a party in third class.
Aware of Cal and Ruth’s disapproval, Rose rebuffs Jack’s advances, but realizes she prefers him over Cal. After rendezvousing on the bow at sunset, Rose takes Jack to her state room; at her request, Jack sketches Rose posing nude wearing Cal’s engagement present, the Heart of the Ocean necklace. They evade Cal’s bodyguard and have sex in an automobile inside the cargo hold. On the forward deck, they witness a collision with an iceberg and overhear the officers and designer discussing its seriousness.
Cal discovers Jack’s sketch of Rose and an insulting note from her in his safe along with the necklace. When Jack and Rose attempt to inform Cal of the collision, he has his bodyguard slip the necklace into Jack’s pocket and accuses him of theft. Jack is arrested, taken to the master-at-arms’ office, and handcuffed to a pipe. Cal puts the necklace in his own coat pocket.