Guero Davila is a pilot engaged in drug-smuggling for the local cartels. Teresa Mendoza is his girlfriend, a typical narco's morra, quiet, doting, submissive. But then Guero's caught playing both sides and in Sinaloa that means death.

Teresa finds herself alone, terrified, friendless and running to save her life, carrying nothing but a gym bag containing a pistol and a notebook that she has been forbidden to read. Forced to leave Mexico, she flees to the Spanish city of Melilla where she meets Santiago Fisterra, a Galician involved in trafficking hashish across the Strait of Gibraltar. When Santiago's partner is captured, it is Teresa who steps in to take his place. Now Teresa has plunged into the dark and ugly world that once claimed Guero's life - and she's about to get in deeper . . .