The story is about Juan dela Cruz. Juan was an orphan. He was taken care by a Catholic priest named Father Cito. Father Cito taught Juan good values and faith on Jesus. Juan was so devoted to Jesus Christ that he called him "bossing" (Filipino word, for "boss"). On one day, Father Cito was killed by a thief. Juan went to Quaipo, Manila with Lola Belen after Father Cito's death. Juan does not know that he is a half-aswang, the son of the "Haring Aswang" (King of the Aswangs) and the "Anak ng Dilim" (Child of Darkness). According to a prophecy, the Anak ng Dilim is fated to lead the aswangs and take over the human race. However, Juan's mother, Amelia, is a human and a "Tagabantay" (Guardian). The Tagabantay's duty is to protect the humans from the aswangs. The Tagabantay also wields a weapon called the Bakal na Krus.