Under the Skin is a psychologically introspective, noir novel based on a real-life story: in 2005 the body of an unknown prostitute was found on the Eje Transversal train line; she has a strange erotic tattoo. Coincidentally, or otherwise, the tattoo is the same as that of a man killed in Darnius a couple of years before. From this base, the plot unfolds two stories simultaneously: Pau Perellós, a writer whose wife has just left him and Paula Galkiewick, a Polish prostitute who he meets on the street. Paula's disappearance leads Pau into the underworld, on a journey to hell which will help him to pull through his creative and emotional crisis.