Viceroyalty of Peru, 1623. On a black night like no other, the devil became flesh in the City of Kings when, in the convent of Santa Clara, a novice gave birth to a horrifying beast with two heads, forked tongue and eight limbs. The birth of the spawn coincides with the appearance in the capital of a woman named Rosa, who, it is said, is able to speak with God and the Devil. Witch or saint, she has become the target of the Holy Office, which will not rest until it reveals the true intentions of the young woman, as well as her possible relationship with the demonic birth and the terrible events that will be unleashed with it. In a city mired in crime and corruption, ravaged by bad omens and winds of uncertainty, Alonso Morales, a novice bailiff of the Holy Office, will bear witness to the arrival of the Evil One as he discovers how difficult it is to distinguish the paths that separate good from evil.