An Alien Enemy 1918

Neysa von Igel, who is living with her supposed grandfather, Adolph Schmidt, loves America, although she believes herself to be German-born. Unknown to Neysa, when she was three years old, her father and mother, both American-born, were killed in Germany by Emil Koenig, who, in punishment, was sent to the United States to work in the interest of the government of the Fatherland, and who is now associated with Schmidt in his manufacturing enterprise. Koenig demands that Neysa work in behalf of Germany. She revolts and escapes to the home of David Hale, who had been her grandfather's attorney, but who is now in the service of the United States Government. Hale and Neysa are married and depart for France, where the girl again encounters Koenig, and, after many thrilling adventures, she kills him in self-defense. - Written by Moving Picture World synopsis, from IMDB.com