Some women don't mind a little smoke, but Jenna Edwards is not one of those women. Having already lost a husband to poor health and raising a son with chronic asthma, she has become health conscious to the point of near obsession. On her arrival at Cra-Z-Horse Ranch, she finds herself joining a close-knit staff, including the veteran cook who brands cattle in her spare time and has no room for a fancified, eastern nutritionist in her kitchen, and Jake Chisolm, the ranch owner who will do nearly anything Jenna recommends to make the ranch successful and to avoid another heart attack.
Although the handsome and enigmatic wrangler Wayne Collier stirs an attraction she can't deny and opens her eyes to how being overprotective has hurt Brian's morale and resulting health, she refuses to get involved with someone who ignores his health, especially if it's a habit that aggravates her son's asthma. As their relationship develops from friendship to something more, she'll do anything to make him quit and to keep her own secret addiction hidden.
Wayne has no use for a woman in his solitary life. After watching his stepmother drive his father to the grave with her constant demands, he's convinced all women manipulate men. But when he sees Brian suffering from asthma, he can't help intervening to give him the challenging adventure and happiness he needs to thrive. He finds himself caring for both of them, but when Jenna fails to accept his smoking, he's forced to choose between the family he's grown to love and the precious freedom to be himself. Then Jenna goes too far, transforming the ranch and his long-time home in a way that threatens his entire way of life.
Jenna's son, Brian, is all too willing to move to the place he's always dreamed about. Western movies and fantasies of the father he never knew being like Buffalo Bill help him cope with a life plagued by poor health and restricted activities. As he overcomes the debilitating symptoms of asthma, he finds a best friend in Tommy, Jake's grandson. Tommy shares his dreams of the west and misses his own father, who is always too busy for him. Like Wayne, Tommy pushes Brian's comfort zone until they find themselves in a predicament that threatens their very lives and forces Brian to tap into a strength no one knew he had.
Then, in their misguided attempt to get his mother to marry the man he idolizes, Brian unwittingly does the one thing guaranteed to drive them apart forever. For one glorious buffalo summer, his dreams of having a father come true, but unless Jenna and Wayne can resolve their differences, their love will not be strong enough to survive the seasons.