During World War I, young women thought to have sexually transmitted diseases were seen as a threat to the war effort and forced into quarantine. In Charity Girl, Michael Lowenthal's flawed historical novel, 17-year-old Frieda Mintz has just landed a job at a Boston department store. After the ''Committee on Prevention of Social Evils Surrounding Military Camps'' accuses her of infecting a soldier, she's sent to a medical detainment camp. But the story never compels. It's not that the events are far-fetched in today's political climate, they're all to easy to believe it's that the characters, Frieda included, are so wooden.