Tim Lake (Domhnall Gleeson) is 21 and lonely. In the harsh morning light following a depressing New Year's Eve party, however, he discovers a family secret that will change his life forever. Entrusted by his father (Bill Nighy) with the knowledge that the men in their family can time travel, Cornwall native Tim relocates to London to study law, and find a girlfriend. The moment Tim locks eyes with gorgeous Mary (Rachel McAdams) he knows he's found the woman of his dreams. But as soon as they've fallen in love, an unexpected glitch in the time travel renders them complete strangers again. Now, in order to win back Mary's heart, Tim will have to travel into the past time and again. Eventually, he seems to master the process, using his unique talent to create an unforgettable marriage proposal, ensure his wedding to Mary goes off without a hitch, and circumvent a massive traffic jam that blocks their route to the hospital when his wife goes into labor, but in time Tim discovers that the true key to happiness lies not in his ability to fix the problems of the past, but instead make the absolute most of his life in the present..