The Doctor and the Woman (1918)

The mysterious "K" takes a humble job and falls in love with his landlady's daughter, Sidney Page. Sidney discourages her boyish admirer, Joe Drummond, and seeks training as a nurse. Infatuated with the head surgeon, Dr. Max Wilson, she accepts his proposal, which infuriates nurse Carlotta, who also loves Max. Carlotta lures Max to a roadhouse, where Joe, mistaking her for Sidney, shoots Max. K appears and, assuming his true identity as the famous Dr. Edwards, saves Max's life by performing his "Edwards operation."