Mary Doone (Theda Bara) lives in a tenement parish house run by Pastor Elliott Clifford (A. H. Van Buren). Mary joints the front as a nurse, and meets war correspondent Lloyd Stanley (Stuart Holmes), whom she had known from London. Stanley is about to take advantage of her when their hospital tent is bombed. Mary finds the body of a young girl in the tent. The young girl is Ethel Wardley (Madeleine Lee Nard), who is the niece of Lady Clifford (Lucia Moore), mother of Elliott Clifford. Mary assumes Ethel's identity and is received by Lady Clifford as her niece. Elliott falls in love with Mary. Stanley returns to London with Ethel, who has recovered from her wounds. Mary confesses what she has done, and despite Lady Clifford's pleas for her to stay, she returns to the parish house to work with children.