BEHIND THE GREEN DOOR #4 - A PENNY PARKER MYSTERY By MILDRED BENSON - GUNSTON CLASSICS -is the heroine of a series of 17 books written by Mildred Benson and published from 1939 through 1947. Penny is a high school student turned sleuth who also sporadically works as a reporter for her father's newspaper, The Riverview Star. Her mother, similarly to Nancy Drew's, died some years before, so she was raised by the Parker housekeeper, Mrs. Weems. On her cases she is sometimes aided by her close friend, brunette Louise Sidell, and occasionally Jerry Livingston or Salt Sommers who are, respectively, a reporter and photographer for her father's paper.