Hercules, Prisoner of Evil is a 1961 fantasy adventure movie directed by Antonio Margheriti. A small village is being terrorized by an unknown monster. Hercules (Reg Park) sees the aftermath of the mysterious monster and rushes to warn the King. The King is a simple man who misconstrues everything Hercules tells him of the monster and decides Hercules is in control of the beast. Fearing an attack by the monster and Hercules, the King orders his men to stop Hercules. Meanwhile, Hercules' brother, Ilo (Ettore Manni), is returning home after many years of traveling. As he is returning home, he is attacked by the enigmatic monster. The attack on Ilo leaves the two brothers very suspicious of each other. As the brothers struggle to trust each other, one of them learns that the other is having an illicit affair that threatens to destroy the small village and everyone who lives there.