Dave not only enjoys a blossoming career, but also a blossoming romance with Samantha, a beautiful doctor who works in the emergency room. Through a series of misunderstandings, the Chipmunks begin to believe that a marriage proposal is on the horizon. Fearing the idea of an antagonistic stepbrother, Alvin, Theodore and Simon embark on a mission to stop their best friend from ruining their lives.
Dave and the Chipmunks embark on a luxury cruise to attend the International Music Awards. Of course, Alvin can't resist the urge to wreak havoc, soon finding themselves marooned on a seemingly deserted island. As Dave and an unexpected ally launch a search, Alvin and company discover that they are not alone on the island, as they first thought.
The Chipmunks Alvin, Simon and Theodore take a break from pop music and head back to school. Almost immediately, the teens are tasked with saving their school's music program by winning a battle of the bands contest. Though the boys think winning will be easy, romantic and musical sparks fly when they meet Brittany, Eleanor and Jeannette.
After the tree they called home is cut down and shipped to Los Angeles, talking chipmunks Alvin, Simon and Theodore find a new home with songwriter Dave Seville. Despite a rocky start to this new arrangement, Dave eventually discovers that the brave creatures have an exceptional talent for singing. When the three of them perform in front of record executive Ian Hawke, he immediately hires them. Although the group quickly gains popularity, their loyalty is soon tested.