Two sisters living separate lives on different continents are reunited on a Mediterranean Island. The two barely have time to bond and revive family ties as Kate, the elder, meets a group of locals and agrees to an exciting ride on a hot air balloon. But disaster strikes and as the result of a freak accident, the balloon is carried far out to sea. Their cell phones out of range, and the balloon running out of gas, Kate and her friends are battling for their lives. While, back on land, the younger sister, Liz, has become an unwanted "material witness" to a crime. Matters then take a dramatic twist, one that will mark their lives forever.
克洛伊(基拉·艾伦 Kiera Allen 饰)从一出生起就和母亲(莎拉·保罗森 Sarah Paulson 饰)过着相依为命的生活,在她们的世界里,父亲这一角色是从未存在过,也不可提及的。因为早产,克洛伊的健康面临着非常严重的打击,时时刻刻都在遭受着死亡的威胁,可即便如此,母亲也从未放弃过克洛伊,她凭借着自己坚强的力量将克洛伊抚养长大。
克洛伊体弱多病,半身不遂只能依靠轮椅行动,母亲是她和外界唯一的联系,在母亲的帮助之下,克洛伊靠着自学参加了大学的入学考试,正在焦急的等待着考试结果的公布。某日,克洛伊对自己每天都要服用的药物产生了怀疑,通过种种调查,她震惊的发现这些药物正是导致自己无法行走的元凶