The fifth daughter of a wealthy Boston physician, Michaela Quinn defies the conventions of post-Civil War society by following in her father's footsteps. After his death, 'Dr. Mike' leaves Boston and moves to the frontier town of Colorado Springs, where she finds the citizens less than thrilled by the concept of a woman doctor. While she struggles to earn their trust, Mike's life is complicated by a growing relationship with mountain man Byron Sully, and the unexpected responsibility of raising three orphaned children.