One of Lassie's puppies, Comet, mistreated by its owner, has turned wild.

Pokey is temporarily quarantined at the Miller farm due to a disease threat. However, when the dog runs away, one of the Miller's neighbors threatens to shoot Pokey on sight to protect his livestock.

Gramps is determined to use the mower before the onset of bad weather but Jeff and Porky are just as set to protect a nest atop the machine that belongs to a rare bird.