After a fight the night before, Erin fails to show up for the flight leaving Lori to travel to the island alone. Meanwhile, in the present day, Erin's refusal to accept the truth of her sister's death leads her to a startling new clue.

As Erin gets closer to the truth of her sister's fate, a final showdown awaits her on the island. Some secrets are worth killing for and not everyone will escape the island alive.