Billy, Paddy, Archie and Sam have been best friends since childhood. When Billy proposes to his much-younger girlfriend, they go to Vegas to relive their glory days. However, the decades have changed Sin City and tested their friendship.

Cal Weaver is living the American dream. He has a good job, a beautiful house, great children and a beautiful wife, named Emily. Cal's seemingly perfect life unravels, however, when he learns that Emily has been unfaithful and wants a divorce. Over 40 and suddenly single, Cal is adrift in the fickle world of dating. Enter, Jacob Palmer, a self-styled player who takes Cal under his wing and teaches him how to be a hit with the ladies.

Billy (Michael Douglas), Paddy (Robert De Niro), Archie (Morgan Freeman) and Sam (Kevin Kline) have been best friends since childhood. So when Billy, the group's sworn bachelor, finally proposes to his thirty-something (of course) girlfriend, the four head to Las Vegas with a plan to stop acting their age and relive their glory days. However, upon arriving, the four quickly realize that the decades have transformed Sin City and tested their friendship in ways they never imagined. The Rat Pack may have once played the Sands and Cirque du Soleil may now rule the Strip, but it's these four who are taking over Vegas.