The spin-off of "Penny Dreadful" tells a story set in the late 1930s in sunny Los Angeles. The fates of the characters are intertwined with the social issues of the time and Mexican-American folklore. Police officer Tiago Vega and his partner, detective Lewis Michener, are busy investigating a murder, but almost all the clues lead to the Devil himself. Will they trust various occultists, myths, and legends, or will they search for real evidence?