Inspector Simón Leira finds himself temporarily in charge of the Santa Margarita police station as the rest of the command staff has commenced their vacation periods. On his first night of duty, a significant incident occurs: a prostitute who had been arrested earlier in the day, facing only minor charges, is discovered dead in her cell. As the investigation unfolds, a series of unexpected events ensue, further complicating the case instead of shedding light on the circumstances of her death. Undoubtedly, these will be the most trying ten days of July for the new inspector.