"I Want a Dog for Christmas, Charlie Brown!" centers on Rerun, Linus and Lucy's lovable but ever-skeptical younger brother. It's Christmas vacation, and as usual, Rerun's big sister is stressing him out, so he decides to turn to his best friend, Snoopy, for amusement and holiday cheer. However his faithful but unpredictable beagle companion has plans of his own, giving Rerun reason to ask Snoopy to invite his canine brother Spike for a visit. When Spike shows up, it looks like Rerun will have a dog for Christmas after all - but then the real trouble begins.