On April 30, 2008, a woman is found dead in the swimming pool of the farm where her ex-partner was keeping exotic animals confiscated by the Guardia Civil. After a few months, the case was closed. Thus begins the struggle of the victim's sister, Rosa, to obtain justice. A tortuous path that she will undertake together with a former civil guard who will help her to demonstrate the shortcomings of the investigation and to uncover a criminal network that the Internal Affairs Service of the Guardia Civil - appearing for the first time on television in Spain - has called "Operation Spider's Web".