The Baker brood moves to Chicago after patriarch Tom gets a job coaching football at Northwestern University, forcing his writer wife, Mary, and the couple's 12 children to make a major adjustment. The transition works well until work demands pull the parents away from home, leaving the kids bored -- and increasingly mischievous.
Steve Martin and Bonnie Hunt return as heads of the Baker family who, while on vacation, find themselves in competition with a rival family of eight children, headed by Eugene Levy,
A young man struggles to access sublimated childhood memories. He finds a technique that allows him to travel back into the past, to occupy his childhood body and change history. However, he soon finds that every change he makes has unexpected consequences.
Pop sensations Alvin, Simon and Theodore end up in the care of Dave Seville's twenty-something nephew Toby. The boys must put aside music super stardom to return to school, and are tasked with saving the school's music program by winning the $25,000 prize in a battle of the bands. But the Chipmunks unexpectedly meet their match in three singing chipmunks known as The Chipettes - Brittany, Eleanor and Jeanette. Romantic and musical sparks are ignited when the Chipmunks and Chipettes square off.