Brand, a young priest, meets three types of people as he makes his way down the mountainside to the tumbledown church in his home valley. The first is a peasant who will not give his own life for his dying daughter. The second is Einar, a young painter returned from travel overseas, and Agnes, his betrothed, who are gaily on their way to the town of Agnes’s parents. The third is a half-Roma girl named Gerd, who taunts him to climb up to her church of ice and snow. In the peasant, Einar and Agnes, and Gerd—the fainthearted, the lighthearted, and the uncontrolled—Brand sees exemplified the triple sickness of the world, and he vows to heaven to bring about its cure.

In the village, Brand gains the admiration of the crowd when he risks his life to aid a man. Later he sees Agnes sitting by the shore disturbed and uplifted by new powers awakening in her when she experiences a vision of God urging her to choose another path. He sees his aged mother, who offers him all her savings on condition that he preserve them for family use. Brand refuses and urges her to give up all her earthly possessions. The mother leaves unrepentant, unwilling that her lifetime savings should be scattered. By these encounters Brand is convinced that his mission lies close at hand in daily duties, even if he is unapplauded by the world. Just as he is going to return to the village, Einar suddenly appears and demands that Agnes come back to him. Agnes, having seen her vision, refuses to go with Einar, even though Brand warns her it will be gray and sunless in his fissure between the mountains; he demands all or nothing.

Three years pass. Although success marks Brand’s work, he realizes that, married to Agnes and blessed with her love and that of their son Alf, he has yet made no real sacrifices. The tests soon come. First his mother dies, still unrepentant. Then his child becomes ill, and the doctor advises them to leave their icy home or the child will die. When Brand agrees, the doctor points out that, in leaving, Brand will give the lie to his own stern attitude toward others. Agnes prepares to go, but Brand is plagued by indecision. Brand thinks that Agnes, as the child’s mother, should make the decision. When Agnes says that she will abide by her husband’s choice, Brand chooses the only way he thinks compatible with his beliefs, though he knows his decision means death for the child they love.

A year later, the mayor, with elections near, arrives to seek Brand’s aid in building a house for the poor. When Brand says he himself is going to build a new church that will cost the people nothing, the mayor leaves.

Agnes feels that she must challenge her husband with what he demands of others, all or nothing. If she were to return to her old life, Agnes asks, would he choose her or his holy work? When she realizes that there can be only one answer, Agnes rejoices, knowing that for the husband she loves it is indeed all or nothing. Soon afterward she dies, leaving Brand alone.

A year and a half later the new church is complete and a great throng gathers for the consecration. The mayor and the dean congratulate Brand on his great accomplishment. Einar appears, emaciated. He has become a fanatic missionary, and he brushes aside as unimportant the news that Agnes and her child died; his only interest is the faith in which she died.

Einar leaves, but the encounter makes things clear to Brand. He exhorts the people to lead a new life. It was wrong, he says, to lure the spirit of God to their heart by building a larger church. There should be no compromise. It must be all or nothing. He waves them away from the church and locks the door.

When he calls the people to the greater Church of Life where every day is dedicated to God, they lift Brand on their shoulders. Up toward the mountains, he urges them. As the rain begins to fall, the sexton warns them they are on the way to the ice-church. The older ones complain of feeling faint and thirsty. Many cry out for a miracle. They feel the gift of prophecy is on Brand and call on him to speak. Uplifted, he tells them they are waging a war that will last all their lives; they will lose earthly wealth but gain faith and a crown of thorns. At this, the crowd cries out that they were misled, betrayed, and they are ready to stone and knife the priest.

Brand toils upward, followed far behind by a single figure, Gerd. He hears an invisible choir that mocks him, saying his work on earth is doomed. The apparition of Agnes appears, saying he can be reunited with his wife and son if he will blot out from his soul the three words that have characterized his old life: all or nothing. When Brand spurns the tempter, the phantom vanishes. Gerd, with her rifle, catches up with him. She sees that Brand’s hands are pierced and torn, his brow marked with thorns. To Gerd he is the Lord, the Redeemer. Brand bids her go, but Gerd tells him to look up. Above him towers the ice-church. Brand weeps, feeling utterly forsaken. With his tears come sudden release. His fetters fall away, and he faces the future with renewed youth and radiant faith.

In the snow from the mountain heights, Gerd sees a mocking sprite, and she raises her rifle and shoots. With a terrible, thunderous roar, an avalanche sweeps down. As it is about to crush him, Brand calls out to God. Above the crashing thunder a voice proclaims that God is a god of love.