Midnight. A young couple is surprised in their car by a strange prowler when they are about to spend an intimate amorous moment. They are savagely murdered. The next morning horrible events begin to take place in a quiet neighborhood: a three year old boy disappears, a man's head is split open with a stone, a woman is cut open with a kitchen knife, a girl is decapitated... All the events point to the fact that Simon Rosales, a dangerous psychopath, had escaped the night before from the asylum where he was confined. When the corpses begin to pile up, the police start looking for the psychopath who is like a shadow, like a silhouette in the dark.