Wow! This book was definitely not what I was expecting, but I enjoyed it so much! It was definitely way darker than I thought it would be, and I would recommend checking content warnings before reading! Basically, this book was a monster murder mystery set in 1890 London, which isn't a book I was expecting to read this year, but I was delighted by it! Hugh was a great character. He was a nighttime constable who was determined to unravel the mysterious and violent deaths of a handful of male prostitutes while the rest of the police force ignored it, considering the victims less-than. Hugh was joined in his investigation by an entity from another universe/dimension, whose sole purpose was to help Hugh solve the mystery. Jack was a really fun character, and he and Hugh together were a really fun pairing. Jack really did do anything in his power to help Hugh discover the truth and to help him bring those responsible for the deaths to justice. There were so many twists and turns, a lot of action, a lot of gore, and some really great sleuthing! I definitely recommend this book to anyone so long as they don't mind blood and gore, because there is a lot of it, but the story was really great!