The great arms industrialist of Europe, Undershaft returns to his long abandoned family with to wreak havoc, like Mephistopheles, with a new gospel of society's redemption. He is a man of "formidable reserves of power, both bodily and mental, in his capacious chest and long head." His gentleness is that of a "strong man who has learnt by experience that his natural grip hurts ordinary people."
Undershaft understands himself in participating in a greater power that controls the world—not the Salvation Army of God, but the armory proper. The Undershaft firm represents an alternative canon of sorts, charting a long tradition of Saint Andrews who have quietly held Europe under their thumbs and determined the course of history.
Like Cusins, he is bent on winning Barbara, though more for his cause than love. He recognizes an inspiration in her that—as with himself and Cusins—elevates her above the common herd. The three of them must band together to determine the course of society.
As with his predecessors, Undershaft is a foundling who understands himself as having established himself in the world through the force of his will alone. This will has committed him to an agonistic struggle with others. As Undershaft proclaims, a sacred commandment—"Thou shalt starve ere I starve"—set him on the path from poverty to greatness. Through the murderous struggle with others, Undershaft has realized his will. Thus his "bravest enemy" is his best friend, a rival who keeps him "up to the mark." Over and against Christian ideals of human brotherhood, the recognition Undershaft demands from his neighbor is not love but obedience and respect, a bending to his will. Again, the struggle he stages with others is decidedly violent: those who do not submit to his desire must die.