While Lassie and Corey are visiting buffalo country and a hunt to cull the herd for conservation purposes, Lassie finds a calf that has been separated from its mother and reunites the two before the cow can be shot as a "barren cow."
Corey and Lassie visit a private ski lift where the manager plans some additions. The area is currently unsafe, so Corey requires improvements be made before the new ski season begins. An accident reinforces the need for increased safety.
Lassie and Corey visit a wildlife sanctuary where many types of migrating birds gather. Lassie rescues a goose caught on an old fishing line. The goose bonds with the collie and doesn't want to migrate until Lassie plays matchmaker..
Lassie and Corey travel to a forest fire to observe new technology. The paratroopers are using a new infrared tracker. When Corey is lost in the fire area, Lassie carries the tracking device and a radio into the fire.
After a cougar trees a bear cub and his mother falls into a pit, Lassie rescues the cub while Corey helps the mother out of the pit. Once rescued, the mother bear becomes violent. Lassie must reunite the two bears.
While in Florida with Lassie, Corey supervises the loading of a special shipment from Jacksonville to Hawaii. A hurricane strikes the area and while Lassie is searching for Corey, she gets trapped on the ship which sails with her aboard.
Set free from a locked room on the freighter by a crew member, Lassie leaps overboard and swims toward shore. She is saved from a shark by a dolphin then proceeds to go ashore in Virginia and heads for the open countryside.
Landing in Williamsburg, Lassie is accused of being a dangerous wild dog by ., a turkey farmer named Seth Plummer. Lassie is defended by Jebediah Wakefield, an elderly attorney, and his assistant Benjamin.
Lassie leaves Williamsburg and heads for the Virginia hill country. While there she befriends a teenage girl named Maggie Pagget, who has a pet fox named Riddle. Lassie saves Riddle from a neighbor boy and his dogs.
Little Jim is a trotting pony preparing to run a sulky race when two backfires startle him and cause him to injure his driver, Dan. Dan's granddaughter takes over the training but needs Lassie's help to get Little Jim to run.
Lassie finds a beautiful wild black stallion who has injured his leg, so Corey adopts him. The horse, however, misses his herd so Lassie sets him free. After the herd's new leader drives him away, he returns to Corey and his new life.
Lassie is injured when she defends a mountain lion's cub from a wild dog. The cub's mother leads Lassie to water, takes her back to their den to recover, and brings food. Lassie returns the cat's kindness when a hunter tries to shoot her.
Lassie and Corey help Jack deliver special salt blocks to a herd of Bighorn sheep. The males battle for supremacy which leaves an old ram injured. Since there is a wild dog pack in the area, Lassie is concerned about the old ram.
Out on one of her nature walks, Lassie helps an owl family survive after the mother owl is injured by an opossum, Lassie hides and feeds the injured owl and provides a surrogate mother for the owl's eggs until the mother owl can return.
White Horse Falls, a logging town, is failing due to poor lumber management. Corey helps the town by demonstrating new timber technology while Lassie watches over Henry IV, a kitten with a penchant for getting into all types of trouble.
While Corey works with locals on a soil management project, Lassie befriends a German Shepherd and a coyote. When the coyote is shot illegally by a hunter, Lassie brings Corey to doctor the coyote and deal with the hunter.
Barney is a watch dog at a turkey game preserve. He lost a fight to a bob cat and has lost his spirit. When Lassie gets tangled in barbed wire and is prey to the bobcat, Barney comes to her rescue.and gets his fighting spirit back.
A house painter hired to paint the ranger station goes fishing and loses his good luck charm. After two days of bad luck he asks that Lassie help him. A squirrel has the charm and Lassie trades with the squirrel to retrieve the charm.
Lassie prevents a pigeon from attack by a hawk earning the gratitude of Eddie, the pigeon's owner. Spending time with the young man, Lassie goesable for help when Eddie falls down an isolated mine shaft.
Goliath is a huge steer and tourist attraction at a roadside cafe. When the abusive owner beats Goliath. he escapes and injures and man. Lassie helps Goliath hide and leads him away from the men trying to shoot him until Corey can arrive.
Lassie and Corey visit old Ben where Lassie meets the otters. When one otter is trapped, the other comes for help. Ben destroys the traps but meets the angry neighbor who want the otters gone. Corey explains how the otters help the lake.