Little Timmy Martin (Jon Provost) and faithful pup Lassie are carried off in a hot air balloon that is being used as a promotional display at a country fair. After drifting to Canada, they are befriended by a giant,mute Indian (Richard Kiel). Timmy's parents (June Lockhart and Hugh Reilly)
are frantic, as a Mountie-organized helicopter search attempts to locate the missing pair. LASSIE'S GREAT ADVENTURE was originally presented as a four-part television program titled "The Journey."