Nine teenage girls are en route to Hawaii when their plane fails, leaving them stranded on a remote island. Among them we meet Leah, who has survived to tell their story to a pair of federal investigators. Flashbacks offer an intimate look at Leah’s pre-island life, and the taboo relationship that broke her heart.

The castaways are still reeling after a tragic event. Frustrated by everyone else's inaction, Rachel leads an expedition to the island's summit to get a lay of the land. We learn more about her career as an elite athlete, the extreme measures she's taken to succeed, and the brutal truth that she isn't sharing with the others.

Leah, Rachel, and Nora swim out to the plane wreckage and return with a crucial find. Fellow Texans Dot and Shelby search for a cave that might provide better shelter, but their contentious relationship makes matters difficult. Flashbacks reveal heart-wrenching secrets about Dot's home life.

A shelter-building contest turns ugly. Toni provokes strife on her team, and we'll learn in flashback that this isn't the first time her rage issues have caused devastating harm.

When one of the castaways goes missing, a search party heads out to find her. We learn more about Fatin's past, which isn’t exactly the glamorous thrill ride the others thought it was. At the end of their exhausting day, the girls make a shocking discovery that stokes Leah's doubts about the island.

A sudden illness rips through the beach camp, affecting nearly every castaway. As the girls fight for survival, we learn more about Leah's past and how she’s been faring since her rescue.

A tidal surge forces the castaways to relocate their camp. Still suspicious of the island and how they got there, Leah turns her paranoia on one of the other girls, viciously accusing her of knowing more than she's letting on. In flashback, Jeanette's astonishing backstory is unveiled.

Assuming that rescue is imminent, the castaways let loose. The only girl who doesn't feel festive is Shelby, and a look into her past reveals why.

Starvation becomes a very real possibility for the weakened girls. Martha could spare them from that fate, but it would require a sacrifice she's not prepared to make. Flashbacks take us into her past, revealing the childhood trauma that's made it hard for Martha to grow up and rise to difficult challenges. Leah's paranoia about the island escalates to a fever pitch.