Raised in a Japanese-Australian immigrant family of pearl-divers, Kashiko's twin Shinju is found dead, washed up on a beach. After their family business tanks, Shinju becomes an internationally known model for her work as a model for an internationally acclaimed pearl jewelry firm. Before her death, Shinju became addicted to cocaine and alcohol. Kashiko goes to the morgue outside of hours to see her twin's body, confirming Shinju's death. Kashiko returns to her bungalow to find her place trashed. Shinju's ex Tom Lafroy Jr. shows up at Kashiko's place after hearing about Shinju's death. Tom tells Kashiko he didn't kill Shinju, and Shinju got herself in trouble with bad people. The autopsy shows that rather than drown, Shinju was suffocated to death by a giant pearl lodged in her throat. Thomas Lafroy Sr., the captain of pearling ships for the pearl firm that Shinju used to model for and Kashiko dives for, tells investigators that his son and Shinju used to have a romantic relationship. When Shinju called off their engagement, the captain's son, Tom Lafroy Jr., threatened to strangle her. Kashiko meets with Tom, who tells her about a rumor he heard that a stray oyster produced a huge pearl, like the one in Shinju's possession, that was illicitly kept by a pearl diver aboard the Indian Princess. Tom agrees to help Kashiko find out who the diver was in order to find a connection to Shinju's murder. Tom is unable to get the ship records required, but finds out that the diver who might have stolen the pearl was found dead the previous year. Tom and Kashiko go pearl diving together. While on a dive, Kashiko's tether snaps and she almost drowns. As Kashiko recovers on the boat, Tom explains that Shinju lied about him threatening to strangle her. The boat docks at a facility on an island removed from the mainland while they wait out a storm. On the island, Kashiko overhears a conversation between the marine biologist Crowe and another person. Crowe chides the other person for failing to murder Shinju without alerting the authorities to a possible murder, and for losing the pearl to the police. Kashiko remembers the day, years ago, when her sister Shinju gave her the scar on her face she still has to this day. As teenagers, Shinju and Kashiko both had crushes on Tom; Tom chose Kashiko. One day, while hanging out around Dutch Air Force wrecks that had been destroyed by the Japanese decades ago, Shinju, Kashiko, and Tom met racist Dutch tourists. While Kashiko and Tom went off on their own, Shinju was attacked by a tourist who blamed the attack decades ago on Japanese like Shinju. Kashiko and Tom took Shinju back home for her to rest before Kashiko sneaked out to have sex with Tom. When Kashiko sneaked back home, her drunken father attacked her and her mother, before Shinju attacked and scarred Kashiko with an oyster knife in the chaos. Kashiko plans to meet the captain of the ship, Lafroy Sr., to confide in him about hearing Crowe admit to being an accessory to Shinju's death. Lafroy Sr. (Tom's father) meets Kashiko at Sunset Point determined to kill her. Before he attacks Kashiko, Lafroy Sr. admits to targeting the twins years ago for his sexual pleasure. He admits to raping Shinju the night Kashiko had sex with Tom Jr.; Shinju only attacked Kashiko to ruin her good looks so that she would not be a target of Lafroy Sr. Lafroy Sr. also admits that Shinju was blackmailing him for the rape. He reveals that the stray pearl was offered to Crowe and Lafroy Sr. by the diver who was killed in order to make the pearl deal a two way split. Shinju stole the pearl and pretended to throw it in the ocean at Sunset Point. Lafroy Sr. attempted to murder her in retaliation; in reality, Shinju swallowed and choked on the pearl, high on cocaine. Lafroy Sr. attempts to kill Kashiko, but in the struggle falls off the cliff at Sunset Point and dies. While Kashiko dangles from the ledge and struggles to pull herself up, Tom Jr. arrives and saves her. Kashiko tells investigators about Lafroy Sr. and Crowe's plot. She gazes at Shinju's pearl necklace and hopes that she is free of the violence she endured while alive on earth.