Marcella, the wife of Jim Gregory, a Pennsylvania coal miner, elopes with Giovanni, her Lover. She leaves their baby daughter with her husband, Gregory, feeling powerless to give proper care to the little one, abandons her on a doorstep, tying around her neck a note and her mother's discarded wedding ring. Tom and Sara Wentworth are the child's foster parents, and Tom calls her Dorothea, meaning "the gift of God." She grows up in sympathy with him, but wholly misunderstood by her foster-mother, who is much displeased at her propensity for caring for all the stray dogs and cats she can find and turning the Wentworth home into a haven for animals. In later years Dr. Grant Hunter falls in love with Dot and she persuades him to give up his work in vivisection. "Dot" loves Grant, but his suit is frowned upon by Sarah Wentworth. Her husband has inherited a large coal mine, and she wants someone more important than an impecunious doctor for her daughter, "Dot" has never been told of her true parentage. Marcella and Giovanni, after many years of prosperity in Naples, have come to grief. Giovanni, known as the Marquis del Carnavacchi, is the leader of a branch of the Camorra. The Italian Secret Service has discovered his operations, and he tells Marcella, who is posing as his sister, that they will be compelled to go to America. Marcella is alarmed, fearing to encounter her husband. At this time the miners in the Pennsylvania town where Gregory lives are talking of going on strike. Gregory has stirred the much abused foreigners into action, telling them the wages paid them are insufficient. In his friendship for them he has drifted into a branch of the Camorra, where he is their spokesman. Little dreaming that Wentworth is the man who has cared for his child all these years, Gregory leads a delegation of strikers who go to the Wentworth's mansion. He sees Dorothea, but does not know she is his daughter. Later, an accident to him at the mine interests "Dot" in him, and she visits him daily in the hospital, the two being strangely drawn to each other. Giovanni is ordered by the Camorra to visit the coal mine. He represents himself as an agent of the Italian government. Sarah Wentworth welcomes so remarkable a personage as a Marquis, and invites him and his "sister" to make her house their home during their stay. They do so, enabling Giovanni the better to betray Wentworth to the miners, and also to make love to Dorothea, whom he makes up his mind to marry. He tells Marcella that he will divide with her the money he receives as a marriage settlement. An intuitive feeling causes Marcella to oppose the match, and "Dot" herself joins her foster father in objecting, but Sarah is determined to have a Marquis in the family. The marriage settlement is ready to sign, when "Dot" upsets everything by saying that if it costs so much money to get a husband she will remain single. His plans thwarted, Giovanni decides to abduct "Dot" and kill Wentworth. Marcella is horrified, but Giovanni tells her to pack up and be in readiness to leave. Gregory, now recovered, refuses to be a party to the murderous plans of the Camorra members, but carries a message from them to Wentworth. While there, he overhears Sarah upbraiding "Dot" for spoiling the match with the Marquis, and he learns that "Dot" is his own child. Under Wentworth's roof he meets Marcella, and husband and wife join forces in an effort to save their child. Marcella invents a pretext to take "Dot" out of Giovanni's reach, and Gregory remains to fight with Wentworth against the coming strikers, having sent in a call for the police. Gregory and Giovanni struggle and the former is shot. Giovanni is caught by the police, but Gregory has been mortally wounded, and dies giving "Dot" his blessing, but not letting her know that he is her father. Marcella places her daughter's hand in that of Dr. Grant Hunter.