In 1910, city girl Mary Elizabeth Eden marries William Asbury Thompson, a Protestant preacher beginning his first ministry in the rural community of Mossy Creek, Georgia. Mary feels trepidation about the radical lifestyle change, but her love for William helps to assuage her nervousness. While taking Mary to her new home, William engages in a buggy race with Jack Stark, a wealthy, aimless but good-hearted young man from a nearby valley. When William wins, he tells Jack that he must fulfill their standing bet of attending church on Sunday, even though the local townsfolk consider him a black sheep. That evening, Mary meets her neighbors, who assemble at the house to celebrate her arrival. Mary inadvertently angers general store owner Jeff Brock, the wealthiest member of the congregation, when she tells his daughter Jenny that Jack, her secret sweetheart, is waiting outside for her. The partygoers drift away, and William comforts Mary by assuring her that she is the mistress of her own home. That Sunday, during his sermon, William encourages the married couples to stand and repeat their vows, and does the same with Mary. As time passes, Mary learns that part of a preacher's job is reaching out to his congregation, rather than waiting for them to come to him. One day, Mary and William visit the Salter family, who have never attended services, and meet patriarch Tom Salter, a well-educated, bitter man who has taught his three young children that religion is based on superstition. William tries to persuade Salter to allow the children to come to Sunday school, but gracefully exits when Salter refuses. On the way home, William and Mary again race with Jack and Jenny, and accidentally run Brock's buggy off the road. The infuriated Brock chastises William for befriending Jack, but William maintains that it is his duty to care for Jack's soul. Later, Mary worries that Brock will cancel his subscription to the congregation, thereby endangering William's salary, but William soothes Brock by swapping his lively horse for Brock's broken-down nag. Mary's pleasure at her husband's cleverness is forgotten, however, when Dr. Fleming warns the Thompsons that a deadly epidemic is breaking out and many deaths are imminent. Mary, who has never experienced illness and death before, accompanies William as he tends to the sick families, and the hard-working pair and Dr. Fleming become exhausted by the travel between the distant farms. William suggests turning the church into a hospital, and soon the building is filled with patients, including Jenny. Distraught over Jenny's illness, a drunken Jack visits the church, but William promises him that the Lord will not let Jenny die. Mary is heartbroken, as she believes that Jenny will die and that William has lied to Jack, but her faith is restored when Jenny's fever breaks and the epidemic ends. Later, William and Mary, who is pregnant, take the Sunday school children on a picnic, and persuade the reluctant Martha Salter to allow her children to attend. The happy gathering turns tragic when George Salter drowns in the mill pond, and the grieving Salter rejects William's attempt to comfort him. That night, Mary's baby is born prematurely and dies, and William somberly baptizes the infant at Mary's insistence. Mary is overwhelmed with grief, and as the months pass, neglects William and herself. She is reminded of the necessity of making herself appealing to her husband, however, by the appearance of the beautiful Mrs. Billywith, a lonely married woman who turns to William for "spiritual advice." Although William remains ignorant of Mrs. Billywith's designs on him, Mary warns her to stay away from him, and begins making herself attractive once again. Soon after, Jack and Jenny elope and ask William to marry them. William performs the service, but the young couple must then go to the city to obtain a marriage license. After they leave, Brock arrives, but William and Mary calm him down and even convince him to pay William for the service. Brock's five dollars become the start of William's Christmas fund, for, after he learns that Salter has told his remaining children that there is no Santa Claus, William decides to provide all of Mossy Creek's children with anonymous presents. William's mission is a success, and when Salter sees how thrilled his children are with their presents from Santa Claus, he wonders if his rigid beliefs have robbed them of the joys of childhood. When spring arrives, William's three-year assignment at Mossy Creek comes to end, and it is time for him and Mary to move to a new community. The Thompsons are bid farewell by their loving congregation, and even Salter steps forward and promises William that he will face the future with an open mind.