Barcelona, 1843. The exterior walls drown the city and the chimneys fill its skies with smoke, making them as dirty, dark and irrespirable as their streets are, where workers from the numerous factories are coexisting with homeless, beggars and some groups of criminals such as "La Tiña", made up of orphans and thieves that exchange all kind of information that may be worth some money. Miquel Expósito is one of them. Victor's body, his best friend, appears abandoned in an alley. Helped by Andreu Vila, a journalist, and the doctors Mata and Monlau, Miquel begins an investigation that will lead him to discover a strange chain of murders that seem made by the same person and are related with several of the city's most powerful industrialists... and the slave trade to Cuba