The Immortal Flame (1916)

Ada Forbes loves Eugene Cory, but she marries Stapleton, a political boss who promises Ada's father a Senate seat in return for his daughter. After several years of an unhappy marriage, Ada leaves Stapleton and returns to Cory, now married to Alice Wood, to be his mistress. Alice finds out about the affair and confronts Ada, who promises never to see Eugene again. Then, Ada learns that her mother is dying. The double shock of losing Eugene and her mother brings on a breakdown, and Ada is put under a doctor's care. Her round-the-clock nurse falls asleep, however, and a half-insane Ada wanders away, falls into a river and drowns.