Even during Clyde Griffiths's trial, the short, broad-chested, dynamic district attorney of Cataraqui County seems well on his way toward realizing the American Dream. On the make, he struggles for success in the form of additional political and legal power. Eager for victory and fame, he believes in seizing the main chance. Knowing that the strong more often than not crush the weak, Mason is determined to be strong. Certainly he means to conquer those whose boyhoods were less toilsome than his.
Like Clyde, Mason's early poverty and neglect serve as a spur to his ambition. The son of a poor farmer, he early set aside childish things and helped his widowed mother. At seventeen, he began reporting for newspapers in the region, and at nineteen began law studies in the Bridgeburg office of a former judge. After a few years in state politics, he returned to Bridgeburg as assistant district attorney, auditor, and then district attorney for two terms. Married (to the daughter of the local druggist) and the father of two children, Mason sees in Clyde's case the answer to the problem of his political future.
Another spur to Mason's ambition is his sinister-looking broken nose, disfigured as the result of a skating accident in his youth. Although Mason is a type of the Dreiserian superman, he is also rather romantic and emotional. He is sensitive about his facial handicap — "what the Freudians are accustomed to describe as a psychic sex scar." The reader is to understand that significant connections exist between Mason's repressed sexuality, his commiseration for the dead Roberta, and his bias against handsome, wealthy young men. In the light of his gallant sympathy and political ambition, Mason shrewdly, energetically, and boldly defends the lovely dead girl who can neither defend herself nor rebuff her broken-nosed champion.
To prosecute Clyde, the articulate and energetic Mason acts out of not altogether virtuous motives. His primary intention is neither to find the truth nor to achieve justice, but to get himself elected to a judgeship. Although he courageously commits himself to victory, he has much support, both honest and dishonest. Ruthlessly he hurts Clyde, to the benefit of himself, his friends, and his party.
His combative instincts aroused by community support and a faltering defendant, Mason is pictured as a foxhound leaping at its prey. Bullying, sarcastic, and sly, Mason affects oratorical displays which enhance his instinct to dominate a scene. Even before the trial ends, the voters sweep him into office. He continues to pile fact upon fact, witness upon witness, and he introduces mathematical demonstration and physical evidence, including a boat and two small hairs. In the end, Clyde's nemesis, Roberta's avenger, walks royally out of court with his entourage, a conquering hero amid the cheering herd of men.