An American munitions manufacturer and his son become ensnarled with enemy agents from Germany during the First World War.
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.
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.
Richard Randall, a patriotic young lawyer speaks out against food profiteers. When ruthless food combine head, Everett Dearing, blackmails society idler Tony Terle into compromising Randall's wife, Beverly in an attempt to stop Randall's anti-war crusades. Ultimately, Terle is caught and confesses to killing Dearing, leading to Randall and Beverly's reunion.
Frivolous Jasmine Grenfel is torn between the bold Rudyard Byng and the reserved Ian Stafford. Impulsively she marries Byng with the rejected Stafford leaving for South Africa. He proves to be a poor husband, and much heartache follows but when war breaks out Rudyard distinguishes himself in the field, recovering from his former dissipation and the couple are reunited.
Even though his widowed mother and sweetheart, Mary Putnam, disapprove, Worth Stuyvesant insists on going to West Point and becoming a soldier. Ultimately, Mary breaks off their engagement and Stuyvesant goes on a bender. His conduct is reported to the commander, who sends him to the sub post of Del Rio for 60 days of tour duty. There, Stuyvesant meets Lola Montez, an adventuress. With the help of a couple of her pals, Lola gets him drunk and marries him. But Stuyvesant lives up to his duties as a husband and surprisingly, Lola renounces her old ways and becomes a model wife.
An American agent exchanges places in prison with a condemned British officer and brother of a woman he greatly admires and goes to the gallows.
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.
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.
Melia Nobbs, a young Canadian woman, supports both her invalid father Ambrose and brother Henry. When Henry faces arrest for helping himself to his employer's cash, Melia steals the amount from the star of the theater where she has been dancing and offers it to her brother if he will enlist in the army. Henry agrees and goes off to war, making Ambrose proud of his son, but when Ambrose learns that his daughter has been arrested for theft, he disowns her. Melia does not reveal the reason for taking the money and is sent to prison. Meanwhile, Henry fights bravely in France and returns home minus an arm but wearing the Victoria Cross. He finds his sister, weak and worn from overwork, in the prison hospital. Seeing her brother with his medals, Melia realizes that her sacrifices for him and her country have not been in vain, and that in her own way, she has served her country.
U.S. Navy Lieutenant George Blenton becomes drunk at an official reception, and his fiancee, Jane Ravenslee, the captain's daughter, breaks their engagement. After war is declared, George, entrusted with a secret code book to deliver to an English admiral, drinks and loses the book which German spies recover. During a private court-martial he is offered a pistol for suicide. After drinking again, he fires a shot, but still lives. Put ashore on the island of Tafofu "to rot," George, hating the U.S., moves in with Lehua, a half-white who tries to wean him from drink.
While waiting in a hotel lobby for instructions from his government, Ludwig Schumann, an agent of the Black Legion, is enchanted by Marion Washburn, the daughter of a Texas senator. As he is about to speak to the girl, Schumann is stunned to see a young American enter who could be his double. The American is James Walbert, whom Schumann's contact mistakes for the agent. The contact passes to Walbert a photograph of a woman spy, Wanda Bartell, whom the agent is to meet aboard a steamer. Walbert realizes the mistake and determines to protect his country.
Lieutenant Commander Colton, U.S.N., is in love with Caroline Austen, daughter of a prominent political power in Washington. Colton has a rival in James Archer, a journalist of prominence, unscrupulous and secretly in league with the Ruanian Ambassador, who is endeavoring to obtain for his country inside information as to the United States naval resources.
Considered as the one of the first feature-length Turkish movies produced during the reign of the Ottoman Empire, Casus is about a spying adventure which took place in the First World War. The copy of the movie did not survive to the present day.
In Belgium, at the outbreak of the war, Russian agent Olga Raminoff shoots at a German general when the enemy enters town. Ray Bourke, an American traveler, gives her the protection of his name, but nevertheless both are sentenced to death. They are rescued by an allied rescue plane and later, bound for home, Ray meets an old college friend, Curt Schreiber, who is in the service of the German government. Schreiber has important papers to be delivered to Washington and, knowing that he will be searched on board ship, gives them to Ray. Olga beseeches Ray to give the papers up for her sake, but his word to Schreiber is sacred. Nearing America, Ray tells her that he will make an effort to return the papers if she will marry him.
After a prologue where we are shown the backgrounds of Wilhelm II and Woodrow Wilson, we see the story of Conrad Le Brett from Alsace-Lorraine. Forced to fight for Germany Conrad, sees soldiers taking girls into a church to rape them and kills one who murders a baby. Shot in the encounter he is taken to a Brussels hospital run by nurse Edith Cavell where he falls in love with American nurse, Amy Gordon. After Edith Cavell assassination and the murder of Conrad’s sister Vilma by the evil Lieutenant Ober Conrad honors her dying request that he go to America and defend Alsace-Lorraine's reputation. Once there he convinces President Wilson that Alsatians should be allowed to enlist. Fighting with the "doughboys," Conrad kills Ober, and after the armistice, returns to Amy.
A criminal mastermind uses a "death ray" machine to bring down government airplanes. Police dog, Silverstreak, aids in capturing the insane inventor of the machine. Masked aviator Pilot X is part of the "Air Hawks" gang who threaten the Baker Aircraft Company. Pilot X's actions are focused on stealing Baker's Aerometer, a revolutionary navigational instrument. World-famous aviatrix, Fawn Nesbitt, aids in combatting the attacks on Baker's aircraft.
Captain Terrance Connaughton loses his stable of horses in a card game with Algernon Cravens.
Equipped with an RAF uniform, an English accent, a photograph of his "wife" and a packet of Players (cigarettes), a German agent is parachuted into occupied Belgium to create anti-British propaganda. Unfortunately for him he chooses a night when the Belgian resistance are smuggling the crew of a British bomber home across the channel. Before he knows it he is landing on the south coast of England. With MI5 hot on his trail, the fugitive tries to contact his old German émigré friends in London. But they have all been interned on the Isle of Man. How will he escape back to Germany ?
A young woman's sweetheart fights for the Union Army, while her brother fights for the Confederates.