NIL by Lynne Matson
On the mysterious island of Nil, the rules are set. You have exactly 365 days to escape--or you die.
Seventeen-year-old Charley doesn't know the rules. She doesn't even know where she is. The last thing she remembers is blacking out, and when she wakes up, she's naked in an empty rock field.
Lost and alone, Charley finds no sign of other people until she meets Thad, the gorgeous leader of a clan of teenage refugees. Soon Charley learns that leaving the island is harder than she thought...and so is falling in love. With Thad's time running out, Charley realizes that to save their future, Charley must first save him. And on an island rife with hidden dangers, their greatest threat is time.
The sequel, Nil Unlocked, will soon be available in the library.
(Synopsis taken from the book's back cover.)