It's 1841 & Queen Victoria has just had her first child. The city is bustling with gas & steam powered industry & it's a time of great change. This is reflected at the Metropolitan Detective Police Force where forensics is in its' infancy. Det. Inspector Owen Endersby began his career as a Bow Street runner, the young coppers who favoured fists over evidence when it came to getting a conviction. He embraces the new scientific methods of "deduction, reliable witnesses & proof". But his latest case is keeping him up nights. Two identical murders have been committed. In each case, a scarred & grubby man broke into a work house, killed a matron & kidnapped one of the young girls. Both children were named Catherine & both were left outside the gates. Endersby & his trusty sidekick Sgt. Thomas Caldwell employ "modern" techniques, don disguises & enlist the help of scam artists & pickpockets in an effort to nab their man. But they're just a little too successful. Despite the man's distinctive appearance, they soon have an embarrassment of suspects. Meanwhile, in a small town outside the city, a sickly woman begins to write a confession of her sins. She was once a work house matron, known for never sparing the rod. Her story & those of each of the suspects are interspersed with the current investigation.