Toronto, January 1896. Schoolteacher Amy Slade is concerned when Agnes Fisher, a quiet and withdrawn pupil, faints during her lesson. Although she suspects that Agnes is mistreated at home, Miss Slade is unprepared for what she finds inside the girl's desk: four shocking photographs, one of which depicts the thirteen-year-old in an obscene pose. When Agnes fails to attend school the next day, her distressed teacher takes the images to police. Surely these photographs are not related to the anonymous letters being sent to the station, accusing Sergeant Seymour of wicked and illicit activities? The thought is too disturbing for Detective William Murdoch, who vows to find the missing girl and the photographer responsible for the despicable crime.