Tom, the son of Mr. Wright, a retired business man, leaves to complete his medical course at college. Mr. Wright accompanies his son to the depot, where he meets an old friend of his, who is sending his nephew, Bob Farrell, to the same college. A year later, Bob loses the last cent of his allowance in a game of cards, and returning to his room he discovers where Tom leaves his money. He is caught in the act by Tom, and the next morning Bob is expelled from college and disowned by his uncle. Left to shift for himself, Bob chances to meet a man by the name of Falk, who is chief of a band of smugglers. Falk offers him a position, and Bob accepts. In the meantime Tom has received his diploma; he introduces James King, connected with the Secret Service, to his sister Nell. One night a week later Tom receives an urgent call. Jumping into a taxi he orders the driver to make haste, and in turning a corner they strike a woman. Tom assists her home and discovers that she is the proprietress of a gambling house. While attending to the injured woman, Tom is surprised to hear the voice of his former roommate, Bob Farrell, who is still a patronizer of the card table. Farrell offers the doctor his hand, but he turns away, which aggravates Farrell. Suddenly a confusion is heard in the other room. Farrell realizes that the house is being raided, and while attempting to escape he is prevented by a policeman. In the tussle Farrell draws a gun, fires, and mortally wounds the policeman. The doctor, re-entering the room, stumbles over the body of the dead policeman, and stooping down to examine the man, picks up the gun which was dropped in the tussle. He is found in that position by the inspector, who has captured Farrell. Farrell accuses the doctor of the shooting. Next morning Tom's father reads the report that his son is held for murder and succumbs to the shock. At the trial Farrell's false testimony and the circumstantial evidence prove fatal to Tom, who is sentenced to twenty years' imprisonment. While in prison, Tom writes a letter to his sister, requesting her to seek the services of James King in watching Farrell, whom he believes fired the fatal shot. Nell, delivering the letter, sees Falk talking to a Chinaman in the same building, and she mentions the fact to King. He is interested, as he has just received information that a clever band of smugglers has been operating on the border. He reads Tom's letter and leaves with the girl, who stops him at the corner, where she recognizes Farrell talking to the same Chinaman. King's suspicions are aroused. He orders Nell home and shadows Farrell to the back door of a saloon, where he is discovered by the bartender, who makes an outcry and springs upon him. The noise attracts the attention of Farrell, and one of his gang who hastens into the room. But the detective breaks away. The next morning King intercepts an important telegram sent to Falk from Farrell. In the meantime Tom is dumbfounded to see one of the guards struck down by an outraged prisoner. Left alone with the fallen guard, he dons the guard's suit and makes his escape. King tracks Falk to a railway station, where Falk steps into a waiting auto and starts off, followed by the detective in another auto, which breaks down; he starts after Falk on foot. He sees an automobile and recognizes the occupant as Tom's sister, Nell. He quickly explains the situation and jumps in and starts in pursuit. Upon arriving at a cross road they see Falk's machine stop at a building, and the detective makes his way to bushes across the way from the house; he recognizes Falk and Farrell and two smugglers placing two Chinamen into the automobile. Hastily retreating he comes back with Nell, and arrives just as the machine starts off with the Chinamen. Telling the girl to remain and watch the building. King returns to the machine and follows the smugglers, who recognize him and open fire on him. In the wild chase which ensues the machines are heading toward the railroad track, where a freight train is seen approaching. The smugglers' machine is overtaken by the train, and the Chinamen killed, but the smugglers crawl away from the ruins of the wreck to the nearby woods. Tom suddenly comes upon the wounded smuggler, who begs him to assist him to the rear entrance of the cave. The detective, returning to where he left Nell, finds her gone. Fearing for her safety, he creeps up to the building and peers through the window, but is discovered by Falk and Farrell, who capture him and drag him to the cave. After binding the detective, Falk orders Farrell, who is under the influence of liquor, to watch the detective to see that he does not escape. One of the gang tells him that he has captured a girl hiding in the bushes watching the saloon, and Farrell upon being shown the girl, recognizes Nell and he drunkenly brags to her that he is the man who had shot the policeman and sent her brother to prison. The doctor, finding the detective, sets him free, and he tells Tom that his sister is a prisoner in the cave; he goes for help. Farrell returns and recognizes Tom. A struggle ensues, and Nell, hearing it, runs out of a chamber in the cave just as Farrell and the smuggler are binding the doctor. Nell tries to drag off Farrell, who turns on her; she scratches his face, which infuriates Farrell, and he and the smuggler drag her out of the cave, put her in a barrel and send it over the falls. The doctor's cries for help are heard by the injured smuggler, who, out of gratitude, crawls on hands to him and releases him; he pursues Farrell and Nell. In the meantime King is on his way to get help. He comes upon Falk, captures him, ties him to a tree, and then proceeds to the cave. As they enter the injured smuggler points to the opening of the cave; they leave in pursuit of the others and arrive just as the girl is put into the barrel and sent on its death dealing journey. The doctor and Farrell struggle right on the brink of a precipice, and Farrell, losing hold, goes headforemost into the falls. The detective meanwhile runs below the falls, and with the help of some workmen on the bank, pulls in the barrel and extricates the girl, unconscious but alive. The mother, son, daughter and detective are happy in the extreme at their reunion.
