Colleen develops a teenage crush on Sully after he pulls her out of the path of a runaway wagon. Imagining herself as a damsel in distress and Sully as her knight in shining armor, she purposely sets out to get lost in the woods hoping Sully will rescue her. A freak cold snap blows up and she almost freezes to death before Sully and Dr. Mike find her. Dr. Mike works hard to save Colleen's badly frostbitten hands, and Sully ultimately has a heart-to- heart talk with Colleen.

Meanwhile, racial tensions in town reach a boiling point when Hank accuses Grace of food poisoning which is later proved false when Dr. Mike discovers Hank has been eating meat infected with trichinosis.

After Snowbird gives Mike an Indian pony, Flash, in thanks for her work at the reservation Mike tries to enter the Territory Stakes Race, but race officials, Loren and Jake, won't allow a woman to ride. Dr. Cassidy arrives from Denver with his champion horse and spurns Mike attempts to speak to him colleague to colleague. Dr. Cassidy's rider, Drew, is injured and Mike diagnoses cranial compression, yet Dr. Cassidy refuses Mike's assistance. Drew dies and an angry Mike is determined to enter the race, disguised as a man. Meanwhile, with encouragement from Grace, Brian enters a pie-baking contest and is met with skepticism from Colleen and Loren. To everyone's surprise, Brian is declared the winner. Mike rides the race of her life and wins, but is disqualified when her disguise is revealed and Hank, riding Dr. Cassidy's horse, is declared the winner.

Dorothy, Loren's sister-in-law and old flame, is introduced as an abused wife who defends herself against her husband's assault, then seeks shelter with Loren. Marcus Jennings, Dorothy's husband, persuades Dorothy to return home with him, which she does. Later, they have another fight and Dorothy returns. Unfortunately, after the couple's last fight, Marcus is found dead, and Dorothy is the prime suspect. Mike defends her at the trial, but in the end Dorothy is found guilty. At the eleventh hour, Mike performs an autopsy on Dorothy's husband and proves Dorothy's innocence; Marcus was suffering from acute cirrhosis of the liver. Dorothy remains in town and Loren gives her a room at the General Store and helps her get started on her own newspaper, ""The Gazette."" Meanwhile, Snowbird, Cloud Dancing's wife, leaves Cloud Dancing's teepee when tradition dictates he take in a widow as his second wife.

Mike and Sully work to treat a typhus epidemic at Black Kettle's camp, which begins after Mike and Sully unwittingly convince Black Kettle to accept government blankets infected with the virus. Mike is heartbroken and guilt-ridden as she battles the tribe's typhus epidemic. When Matthew comes down with typhus, the town panics and locks the children in the clinic alone with Horace. Colleen treats Matthew and Horace contrives to send the kids out to the reservation to be with Mike. Meanwhile, the town prepares for the Fourth of July, ironically missing the point entirely that the first Americans, the Indians, are being systematically wiped out and further, that the newest Americans, the Immigrants, have just had their camp destroyed by the typhus-fearing townsfolk

Sully takes a job as an Indian Agent, only to discover corruption's rife within the system. Meanwhile, liquor arrives on the reservation, and Snow Bird miscarries due to malnutrition.

Mike and Sully arrive too late to avert Custer's slaughter of the Indians at the Washita River; Brian befriends an Indian boy destined to die at Washita; Robert E & Grace attempt to adopt an Indian baby whose mother was killed at Washita. No Harm Comes To Him: Sean Price-McConnell.

Sully and the kids must help Mike deal with the emotional aftermath of the Washita massacre; Robert E and Grace must return to Cloud Dancing the Indian baby Mike and Sully brought back from Washita