Victoria pays a visit to a mission church in order to give a charitable gift to the local Padre on behalf of the orphanage he runs. While she is in the church, Victoria notices an Indian woman in tribal dress weeping in the church. She also is confronted by a man named Tate, who is bitter because Nick fired him for drunkenness. Before Victoria can react much to Tate's anger, there is a shudder that passes through the church, and suddenly, plaster rains down and timbers fall.
When Victoria recovers, she realizes that there was an earthquake, and that she and Tate are trapped in what must be the basement. Tate knows that it was originally an abandoned mine shaft. They hear cries, and realize that the woman crying is also trapped. She is pregnant and ready to deliver at any moment.
The trio grapples in the rubble of the collapsed church and finds a lantern. Tate later finds a bottle of alcohol half-full, and begins to drink. Victoria fearlessly leads a crusade for rescue, while Tate is cynical and reluctant to help the pregnant woman. In his resentment, he grabs Victoria and tries to force her to drink with him. Furious, she breaks the bottle and holds up the jagged shards at him, threatening him to dare to touch her again. He submits, and again takes up the journey of trying to find the mine tunnel that leads to freedom.
Meanwhile, Jarrod, Heath and Nick are eager to find their mother, of whom there has been no report since the earthquake, which hit their home as well. Audra joins them in their search, against their wishes. After discovering that Victoria was last seen in the mission church, they try to dig their way through the rubble.
There is one person who doesn't want the party to be found alive. The man responsible for the Indian woman's pregnancy is actually married, and a respected storekeeper. She had asked him to meet her at the church to discuss the baby. Pretending to want to help, he joins Heath in a search of town land records to discover the mine tunnels' exits. However, he secretly tries to destroy them, and Heath finds out and eventually learns his secret. The man's wife also is on to his terrible secret, and confronts him after Heath deposits him into the sheriff's custody.
With no will to live, the young woman experiences labor pains. Tate and Victoria decide to try one more tunnel, and Tate argues which one they should try. After Victoria exchanges routes with him, Tate's tunnel collapses and he is killed. Victoria continues, until the woman begins screaming. The baby is coming, and Victoria rushes to help her with delivery.
The Barkley siblings find an old-timer who remembers twenty years back when the mine was closed, and he finds the general spot where the tunnel surfaced. After some looking around, they are able to dynamite open the shaft, and call out to Victoria. She is found, with a newborn baby, and the deathly still mother.
In the final scene, the doctor puts a sheet over the Indian woman, who died in childbirth. The unfaithful husband is given a second chance by his wife, who wishes to adopt the baby. Victoria expresses her need for a hot bath, and the family goes home to Stockton.