Linus and Lucy's younger brother Rerun wants a dog for Christmas, and Snoopy's brother Spike may be the answer.
Captain Saxon, an agent for the top secret Omega agency, has been given the assignment of tracking down and either capturing or killing the crew members of a secret space mission who returned to Earth against orders. It seems that they were all infected with an alien parasite, and they were trying to bring its eggs back to Earth. The eggs were lost in an accident, and both Saxon and the astronauts are trying to locate them.
Charlie Brown and a few of his friends attend a camp, and there they meet Joe Agate, a lying bully who offers to teach kids the game of Marbles without telling them it's for keep. Then he takes their marbles for good. When Rerun is tricked and gets his marbles taken, Charlie Brown must use his own marbles to help get the other kids their marbles back. The only problem is, Charlie Brown doesn't know how to play.
