During the carnival on the island of Neboa, a young woman is brutally murdered with a mask on her face. Lieutenant Monica Ortiz goes to investigate.

The finding of a new corpse suggests that the murderer follows the same steps as those of 1919 and 1989 with the same number of murdered.

New suspects appear in the town's murder cases.

When Ana's backpack turns up, Monica orders Ana's friends to be interrogated again, since there is something they're not saying; she is also on the trail of the thief who stole tape number nine and assaulted Carmela in her home.

Alejandro and Gonzalo are the main suspects; discovering the killer isn't the only problem for Monica; after surprising her daughter with Emilio, she knows she can't lose sight of her for a second.

Monica's daughter is the latest victim of the Urco, forcing Carmela to take the reins of an increasingly compromised investigation; the main suspect is still Gonzalo, but Monica is no longer so sure.

The carnival is coming to an end, and Monica already knows the identity of Urco; her only desire is to hunt him down and avenge the death of her daughter.