A small group of town residents have to band together after a devastating ground invasion. As they struggle to survive, they realize they must stay one step ahead of their attackers, and work together for a chance to strike back.
少女克莱尔（艾玛·罗伯茨 Emma Roberts饰）和海莉（乔安娜·利维斯克Joanna JoJo Levesque饰）是一对靓丽活泼的好友。海莉的母亲是海洋生物学家，她开学之后就要随同家人离开美国前往澳洲。两个好姊妹的即将天各一方，她们趁着这个暑假来到海滩上尽情游玩，心里盼望着一起的日子可以长些，再长些。在这里，她们碰到了一件怪事：一条传说中的美…
