John Brant, his only daughter, Gene, and Jan Karl, a farmhand, live on a farm in Central Africa, near the border of the jungle. The monotony of their lives is stirred by the arrival in the neighborhood of a hunting party, about to enter the jungle to secure wild animals for an American circus. Henry Barium, the young circus owner, heads the party. He prevails on old John Brant to accompany him on the trip and, in turn, agrees that Gene and Jan Karl shall join the expedition. Jan and Gene are "as good as engaged." as the saying goes. Young Barium pays marked attention to Gene as they journey, and Jan grows jealous. One day he comes on the young people when Barium is trying to force a kiss from Gene. In the trial of strength that follows, Barium is worsted. Gene, who loves Jan, does not show that worthy due appreciation of his interference, with the result that he leaves the expedition for the Transvaal mines. Next day a noble, shaggy-maned lion is caught. He is of such dignified mien and enormous size that he is named Thor, lord of the jungle. Other wild animals are secured and the party starts on the return journey. When the Brant farm is reached. Barium gains the consent of Gene to accompany him to America, where he promises to make her queen of the circus. John Brant strongly opposes Gene's departure; but in vain. On the voyage to America. Gene discovers the true character of Barium. He is both gambler and drunkard, and attempts to take liberties with her. On her arrival in America, she is penniless, and is forced to work in the Barium circus, where she learns still more of the owner's vicious nature. Her mail is secretly destroyed by Barium and she believes herself forgotten and forlorn. Barium hatches a plot for her undoing, but "Billie," the hunchback, who is devoted to Gene,, discovers it and saves her. He is aware that Gene spends much of her spare time near Thor's cage, and he plans so that Barium will join her there on a certain night. In the meantime, he files the bars of the big lion's cage, shortly before the meeting. Gene is ignorant of "Billie's" plans, and is shocked when Barium appears in a drunken state and attempts to attack her. She screams, and Thor breaks through the half severed bars and kills his master. The circus authorities decide on killing Thor; but Gene begs for his life. After much wrangling they consent and Thor accompanies Gene back to Africa and freedom.