A young woman has washed up on the shores of Amity Island, surrounded by boat wreckage, with no sign of any other surviving shipmates-and no recollection of who she is or where she has come from. She wakes up on the moonlit beach just as the shark makes its first appearance, and the next morning when Chief of police Martin Brody finds this young girl, the only witness of a young drifter's death, she suddenly becomes much more significant to the island and to the story about to unfold within it.