Hiraga Joseph Kou and Roberto Nicholas are sent in San Rosario's abbey in Northern Mexico to investigate about a supposed immaculate conception of a young nun, sister Dolores. That same night, however, one of the abbey's priests is found horribly dead, and shortly after a new apparent miracle occurs.

The miracle of the stone's tears is easily explained, but new murders taunt San Rosario. Joseph and Roberto think that part of the answers could lie in the abbey's ancient history, but the other priests' hostility doesn't allow them to investigate further.

Dark secrets emerge from the past while Joseph and Roberto keep on investigating about the chain of deaths in San Rosario. And when the bloody runes found in the church prove to be a famous phrase from the "Mein Kampf", this leads the two priests to the most dramatic discoveries.