Set in the American Southwestern town of San Carlos, For the Love of Mike centers on Father Francis Phelan, who arrives at St. Joseph’s parish to take over from his old friend, the beloved but ailing Father Walsh.
Father Phelan intends to pursue Father Walsh’s passion project of building a new church for the poverty-stricken, mostly Indian parish.
Father Phelan meets Michael Little Bear, an orphan who lives at the rectory and cares for Father Walsh. Mike hopes to become a doctor and has a menagerie of animals whom he has saved and cured.
The elderly priest is an uncooperative patient when the Protestant Dr. Henry G. Mills tells him he must stay in bed and rest. Although Father Walsh, who knows how ill he is, complains that Doc Mills is working against the interests of the church, he actually respects the physician.
Mike tells Father Phelan how much he hopes that Father Walsh will have his new church, and Father Phelan tries to let him know that the priest may die before the money for the church be raised.
Mike sees a poster announcing a quarter horse race at a county fair with a $2,000 prize. Mike then announces his intent to enter his horse Pueblo in the race, and Doc agrees to examine the horse the next morning.
Although the horse once had a broken leg, Mike had set it carefully, and when the two friends test Pueblo, the horse’s speed surprises even Doc. Mike and Doc meet every morning to train Pueblo, and Mike’s friend, Tony Eagle, brings his horse to pace Pueblo. Impressed by Pueblo’s chances, Doc gives Mike the entry fee.
After Father Phelan asks Doc about the horse and Mike’s plan to race it, he gives Doc the church building fund and some of his own money. Father Walsh then reveals to Father Phelan that he, too, knows about the race and would like his money “invested,” hoping to support Mike’s education.
At the fair, Doc encounters Rex Allen, the cowboy celebrity and horse breeder and his trainer, Ty Corbin. Doc places a ten-to-one bet with Rex for Pueblo to win, and as the horses and their riders line up for the race, Rex recognizes Pueblo as the offspring of his best stallion and a mare that ran away one night a few years before. Mike rides Pueblo to a glorious victory, and Rex pays Doc $5,500 in winnings. When Rex asks Mike where he got the horse and then tries to buy it, Mike refuses and lies about the horse’s origins. Later, Father Phelan tells Doc that Father Walsh wants to keep the money, including the winner’s purse, for Mike’s education, and Rex phones to say that Mike’s story that the government gave Pueblo to the Indians was false. Father Phelan confronts Mike and Mike tells him that he found the dying mare and colt in the hills, and knowing that the coyotes would get them, stayed with them for two days, then brought the colt back to the church on a stretcher. When Rex and Ty show up at the rectory, Father Phelan reads them a letter from Mike in which the boy apologizes, saying that he had to leave because his lying brought shame upon his people. After Rex offers to bring over horses for a search party, Tony leads the group into an area called “Sangre de Cristo,” where he suspects Mike has sought refuge. Tony’s pregnant wife goes to stay with Father Walsh, and when she shows him Mike’s letter, the priest becomes upset and prays for Mike’s safe return. Meanwhile, Mike is growing weary, and unknown to him, is being stalked by a cougar. Father Phelan and Tony discuss Mike’s lie, and Tony teasingly assures the priest that even though Mike lied, he also stole a horse from a white man, making him almost an Indian hero. When the search party locates Mike’s deserted camp, Tony and Father Phelan decide to proceed on foot, while Rex and Doc check another trail. Mike, meanwhile, hungry and exhausted, falls down a hill, injuring himself.
After he orders Pueblo to go home, the horse hears the cougar growling at him and whinnies, chasing off the cougar and alerting Tony and Father Phelan, who find a delirious Mike and carry him to safety. Back at the rectory, Rex gives Father Phelan a blank check for the cost of the new church, and Mike apologizes to Rex.
When Rex tells Mike to keep the horse, Mike refuses, prompting Father Walsh to strike a compromise: the two will be partners, with half of the horse’s winnings going for Mike’s education.
The group sings “Happy Birthday,” the only happy song they all know.
