The long-awaited third entry in the popular comedy/sci-fi series finds the universe on the brink of destruction-and Bill (Alex Winter) and Ted (Keanu Reeves) still haven't written the song that was meant to prevent that very catastrophe. Can another wild trip through time and a little help from their respective daughters (Samara Weaving and Brigette Lundy-Paine) get the tune penned before all of reality is lost forever?