Karl "Curly" Casterline, a wrongfully discharged New York City policeman, finds work on the Midwestern farm of Adolf Bauerle to help the war effort. Curly is attracted to his boss's niece, Mina, but also realizes that Adolf and his cohort, Kurz, plan to blow up a troop train. Curly kills the two saboteurs and saves the train, but he is jailed by the abusive Sheriff Herman Lindig. Although Mina praises Curly for saving the soldiers' lives, he is sentenced to death and is denied a pardon from the governor. After the case attracts national attention, the governor explains that he prolonged Curly's incarceration to draw attention to the danger of German propaganda.
Just prior to World War I, the Kaiser sends Baron von Zeller to inform Emperor Franz Josef of Austria that he is ready to declare war on France. Sensing the impending crisis, the French War Office dispatches secret agent René de Bornay to investigate the situation, and upon his arrival, he cultivates the friendship of Franz Josef's mistress, the Countess Griselda von Arenburg.
French scientists are developing a secret weapon, a gun that uses the mysterious powers of X-ray and ultra violet rays, called a "Ray Rifle." Miss Dalton played the girl that would protect it from German spies.
At a military hall in a Southern mansion the Confederate officers are amusing themselves. Captain Ford is the officer in charge and Virginia, the young hostess, is his sweetheart. At the height of their fun the sentries outside report the approach of Union soldiers. All officers hurry to their commands. At first the Confederates, having less men, attempt to outmarch the Federals. However, after a short time, they change plans and entrench themselves on the surrounding hills.
Hearing that the United States has just declared war on Germany, Bill Durham hurries to a recruiting station to enlist, but because he has flat feet, he is rejected. He falls in love with Barbara Knowles, whose guardian, August Myers, unknown to Barbara, is a German agent. When Bill learns that Myers plans to stir up trouble on the border of the United States and Mexico, he catches the train to New Mexico and routs out Myers' gang of bandits.
A German-American father, loyal to his new U.S. home, finds himself on opposite sides with his son in the wartime conflict between Germany and America. The son becomes involved with German agents plotting against U.S., and the father must decide between his son and his adopted homeland.
Returning from France after the war, John Tabor informs Palma May of her brother's death and offers the penniless girl his help, but she refuses it, preferring to work as a cabaret dancer. Later, John and Palma meet again, marry, and go west to manage a lumber camp, as instructed by John's wealthy father, Jarvis Tabor. Displeased by John's choice of wife, the elder Tabor tests the couple with difficult living conditions, which eventually discourage Palma, and she accepts the party invitation of Keith Merwyn, manager of the cabaret where she starred. Meanwhile, Merwyn effects a disturbance among the lumbermen, endangering John.
Secret Service officer Richard Paget receives a letter from his twin brother John imploring him to take over his identity after he commits suicide, so that Richard can subvert the plans made by the airplane company which John had financed, to make defective planes for the United States to use in the war.
During World War I, the beautiful and patriotic Leslie Selden is courted by two ardent admirers: Jack Wynn, a young man not yet taken by the draft, and Dr. Wolff, a Danish scientist who, in reality, is a German agent. When Jack learns that Wolff is masterminding a plot to bomb several munitions factories and destroy the water system in New York City, he goes to the spy's home and confronts him.
Loyal slave of the aristocratic Dabney family, Dan is overjoyed when Raoul becomes engaged to Northerner Elsie Hammond and his sister Grace becomes engaged to Elsie's brother John. When the Civil War breaks out, the heartbroken Hammonds return North and John joins the Union army. Raoul joins the Confederacy, but his vindictive overseer, Jonas Watts, becomes a Union officer. Watts takes Grace prisoner, but before he can act on his desires, John rescues her.
The hero is a young soldier who is in love with two girls simultaneously. While on the battlefield, the soldier learns that one of his sweethearts has committed suicide. Only temporarily taken aback, he begins to dream of the blissful domesticity which he will enjoy with the other girl upon his return.