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.
| Actor | Role |
|---|---|
 June LockhartRuth Martin | Ruth Martin |
 Jon ProvostTimmy Martin | Timmy Martin |
 Bob HowardSergeant Sprague | Sergeant Sprague |
 Richard KielChinook Pete | Chinook Pete |
| WWalter StockerJohn Stanley | John Stanley |
| HHugh ReillyPaul Martin | Paul Martin |
 Will J. WhiteConstable MacDonald | Constable MacDonald |
 Patrick WaltzPilot | Pilot |
| LLeo NeedhamRanger Henty | Ranger Henty |
 Dick SimmonsNot listed | Not listed |
| PPatrick WestwoodNot listed | Not listed |
 LassieLassie the Dog | Lassie the Dog |