After the killer threatens Marina, Arturo places security in his mother's house to protect his sister as well as to stop her from continuing her investigation. But Marina and Héctor manage to escape and end up at Belle Epoque, a theatre where they believe the killer might be hiding.

The killer has managed to evade the police and Arturo is forced to recognise that there is in fact a killer on the loose threatening the general public. Meanwhile, Marina and Héctor discover a new clue that leads them to the identity of two women who are in grave danger. Searching for them, they end up in the Women's Quarters, where they confront the killer in an epic final battle.

After detaining the killer it seems that Marina will be forced to give up her dream of becoming a cop, but thanks to Castaño the case is reopened. Together they conclude that the killer is still on the loose and the cops propose a plan to catch him: host a masked party for the clients of the House of Water.