Charlie Brown, Snoopy, Lucy, Linus, and the rest of the beloved Peanuts gang make their big-screen debut, like they've never been seen before, in state-of-the-art 3D animation. Charlie Brown, the world's most beloved underdog, embarks upon an epic and heroic quest, while his best pal, the lovable beagle Snoopy, takes to the skies to pursue his arch-nemesis, the Red Baron.

Linus is pushed to his limits when he learns grandma is coming to visit and plans on ridding him of his childish security blanket. As grandma's arrival looms closer, the Peanuts gang tries to help Linus learn to cope without his fuzzy crutch. Lucy is particularly eager to cure Linus' dependency using her own psychiatric techniques, and while Charlie Brown tries to help he just doesn't have the heart to see Linus suffer.