The Bésixdouze expedition was a group of six French researchers, including Danielle Rousseau, who sailed from Tahiti on November 15, 1987. Their ship, the Bésixdouze, wrecked near the Island during a storm while the expedition was attempting to locate the source of a strange transmission. Pieces of wreckage from the vessel washed ashore. All members of the expedition, with the exception of Danielle Rousseau died later that same year. At the time of their arrival, Danielle was already seven months pregnant with her daughter, Alex.
While the team was in the water, their radio picked up a transmission. It was a voice continuously repeating a set of numbers. They tried to find the source of the transmission, but their ship got caught in a storm and eventually ran aground, with the hull breached beyond repair. By February 1988, they were drifting to shore in an emergency raft when they found Jin floating unconscious in the water. They dragged him into the raft and brought him to shore with them.("The Little Prince")
The team continued searching for the transmission that brought them to the Island. Jin decided to follow them to the radio tower because he did not know the way to his own camp from his current location. On the way there, Nadine went missing. While searching for her, the team heard a noise, which Jin identified as the Monster. Moments later, a tree was torn up and Nadine's dead body fell to the ground. Jin yelled at the group to run as the smoke monster made its way through the trees. The Smoke Monster caught Montand and dragged him through the jungle to a declivity in the Temple wall. The group chased him and managed to grab his arm just before the monster pulled Montand down the hole. As they struggled, a tentacle of smoke wrapped itself around Montand's arm, severing it. When they heard Montand calling from the hole, saying he had been wounded and needed help, the members of the science expedition decided to enter the hole, despite Jin's warning to the contrary. Jin convinced Danielle to remain behind for the sake of her baby. As they waited, Jin experienced a time flash and disappeared. ("This Place Is Death")
Two months later, Jin found Brennan and Lacombe dead. Then he saw Danielle on the beach arguing with Robert. She claimed he was not her husband and that he had become infected by the monster. Robert tried to assure her that he still loved her and had not changed. He insisted that the smoke monster was merely a security system for the Temple. Robert asked her to put down her gun. She began to lower her weapon, but Robert raised his own and pulled the trigger. The gun failed to fire because Danielle had removed the firing pin. She shot Robert in the head and Jin cried out in alarm. She turned toward him and recognized him. Insisting that he too was infected, and that he was "the carrier," she began firing at him. Jin rushed into the jungle to hide and experienced another time flash. ("This Place Is Death")
Danielle was one of the two women on the team, and was pregnant with the daughter of fellow team member Robert. Due to the "sickness," she killed several members of her team until she was the last remaining. She survived on the island in seclusion for sixteen years afterward until she was killed by the mercenary team.