A jaguar has been attacking cattle and the watchdog on a Western ranch, and Lassie arrives to help. She gets some unexpected assistance when a cougar, foraging nearby, hears the battle and attacks the jaguar.

Lassie stands guard over the injured watchdog as the jaguar and cougar battle. The jaguar retreats in defeat and Lassie recognizes the cougar as a friend from days past. Lassie summons the rangers to eliminate the hostile jaguar for good.