While in Canada Timmy and Lassie encounter a downed hot air ballonist. By accident they end up in the balloon which takes them into the wilderness. The young boy and his dog must find a way to survive even fending off a wild pig.
A scientist develops a serum that can eradicate scar tissue. He tries it on a girl with a horribly disfigured face. It succeeds, but then he discovers the girl is an escaped mental patient from a local asylum.
