Peter has his heart broken by Sarah Marshall, his girlfriend of five years. Sarah is an actress on a television crime series. After breaking up with Peter, she moves on with her life and her new boyfriend, Aldous, a British rock star. Peter is devastated, and after trying unsuccessfully to put her out of his mind, he decides to take a vacation to Hawaii to unwind. Unfortunately for Peter, Hawaii is also the chosen destination of Sarah and Aldous....

Clare has been in love with Henry her entire life. She believes they are destined to be together, even though she never knows when they will be separated: Henry is a time traveler, cursed with a rare genetic anomaly that causes him to live his life on a shifting timeline, skipping back and forth through his lifespan with no control. Despite the fact that Henry's travels force them apart with no warning, Clare desperately tries to build a life with...