A Voice in the Dark (1921)

Mayhem abounds for two sisters , who both are engaged on the same day: Adele Walton to the scandalous Dr. Hugh Sainsbury, and Blanche, the elder, to Assistant District Attorney Harlan Day. Both girls are suspected of murder when Sainsbury is found shot. Blanche has a motive: Sainsbury nearly dishonored her, and she would prevent his marriage to her sister. The day is by two witnesses, one deaf and the other blind, who reside at the sanitarium where Sainsbury worked, the mystery is solved and the murderer is revealed to be Amelia Ellingham, a nurse at the sanitarium, whom Sainsbury had seduced and failed to marry.