Chicago librarian Henry De Tamble (Eric Bana) suffers from a rare genetic disorder that causes him to drift uncontrollably back and forth through time. On one of his sojourns, he meets the love of his life, Claire (Rachel McAdams), and they marry. But the problems and complexities of any relationship are multiplied by Henry's inability to remain in one time and place, so that he and his beloved are continually out of sync.