1915. Bolshevik Martin Venta, an officer of one of the battalions of Latvian riflemen, returns to Latvia from Siberian exile. The hero establishes a connection with the Bolshevik organization and joins the underground work. Venta's son Limon, who fled from the German-occupied Ventspils, ends up in his father's company. Engaged in underground activities, Martin does not notice that his son falls under the influence of an ardent nationalist, Lieutenant Colonel Ezerin.