Something is wrong in the city of La Bene. It's January, and the midsummer market is in full swing, with a music competition on one side and an exhibit of new magical machines on the other. But the atmosphere sours when rumors of the return of the malarial mosquito fairies inflame angry crowds and suspicion of foreigners. Detectives Rocío Díaz Rossi and Hala Haddad Sosa are on the spot when a conflict between an angry crowd and a boat full of despised river folk boils up. Rocío is known for her people skills and Hala has a talent for putting unlikely clues together. But nothing is what it seems in this case. Is their city at risk? Or are the stakes much more personal?