Loren, the unforgiving father-in-law, threatens to take back Sully's homestead.

Michaela worries when Charlotte's husband, Ethan Cooper, comes back to the family he abandoned, convincing almost everyone of his newfound ways.

Dorothy thinks she's pregnant, but Dr. Mike's exam reveals there are other problems going on. The upcoming Sweetheart Dance causes trouble between Sully and Dr. Mike. Colleen and Becky squabble over a boy, while Dr. Mike suspects something fishy going on between Sully and Dorothy.

The town hires a new school teacher.

Dr. Mike discovers a lump in Dorothy's breast and tries to convince her to have surgery. Hank tries Ladies Night at the saloon, and Jake and Loren have a plan to get free drinks. Colleen deals with hurtful boyish pranks from classmates.

Dr. Mike has a hard time accepting Dorothy's decision not to have the surgery that will save her life. Jake tries to escape the two men who kidnapped him.

A newspaper report of a comet's imminent collision with Earth causes hysteria in town over the end of the world.

Colleen and Brian's biological father Ethan returns to town with a new wife, intending to take the children away from Dr. Quinn. The children don't want to go but a court hearing seems to work against Sully and Dr. Mike, who they consider their parents.

Colleen and Brian run away to keep their father from taking them away from Dr. Mike and Sully. After they are found it's discovered Colleen has developed pneumonia. Dr. Mike realizes she has to let them go to save them.

The town puts on a production of "Romeo and Juliet". Brian tries to learn what love is so he can write a paper for school.

A teenage Belle Star robs the saloon with the Younger brothers and is shot. Dr. Mike takes her home in an effort to show her a real home life, attempting to turn her from her life of crime.

As Dr. Mike becomes increasingly absorbed in her romantic life with Sully, Colleen, feeling rebellious, joins her school friends in dangerous and questionable escapades. When Brian also begins to feel ignored, Mike and Sully realize how important it is to balance their new life.

When a stranger is convicted of raping a young girl and murdering an old man, he is sentenced to death. Some people are conflicted about whether or not it is right to take "an eye for an eye".

Dr. Mike's dearest friend from college comes to visit her in Colorado Springs, both women are initially happy to see one another, but soon resort to their competitive relationship of years past.

Dr. Mike is nominated for Colorado's Woman of the Year and the town regales the judge with her accomplishments. Hank's Nana comes to visit and he "borrows" Myra and Samantha to pose as his family.

Dr. Mike returns to work after giving birth to Katie, but has a hard time trying to balance her professional life, wifely duties, and being a new mother. Sully feels neglected.

Dr. Mike is charged with malpractice and must stop treating patients during the lawsuit, leaving medical matters to the young and reluctant Dr. Cook.

When Sully is offered a job helping to survey the new National Park at Yellowstone in Wyoming, Dr. Mike is faced with the prospect of leaving her practice and all their friends and moving into the wilderness. With Sully no longer acting as the local Indian agent and banned from the Indian reservation, Dr. Mike realizes that it is important for him to have work that is meaningful to him. Leaving everything and everyone she knows and taking their new baby into the wilderness, however, is a daunting prospect for her. Meanwhile, as Matthew and Emma think about marriage, Brian agonizes about his first date at the Sweethearts' Dance, and Dorothy teaches Cloud Dancing some ball room dances while he provides her with background on Indian customs for a book she is writing.

Dr. Mike's mother and oldest sister visit for thanksgiving just as an outbreak of diphtheria hits Colorado Springs.