David, a college student, is looking for a job. He is hired by Dr. Stoner as a lab assistant for his research and experiments on snakes. David also begins to fall for Stoner's young daughter, Kristina. However, the good doctor has secretly brewed up a serum that can transform any man into a King Cobra snake-and he plans to use it on David.

Baron Zorn keeps his teenaged children locked up and drugged, fearing that his insane wife passed along a congenital curse to them before her own suicidal death. Elizabeth escapes for a brief tryst with a local before being recaptured and subjected to a bleeding process to 'draw out the bad blood.' Emil keeps trying to escape, but is thwarted time and again by his aunt Hilda who runs the house like a prison. One reason the siblings have to be kept apart, is their incestuous attraction to each other. Local wenches are being murdered in the woods, and the superstitious peasants think demons are responsible. A wandering Priest dedicates himself to root out the evil, but isn't taken seriously. Arriving at the castle are two more interested parties: Mountebank scientist-huckster Falkenberg stands to make a small fortune if his strange apparatus can cure the children of their inherited evil. Young Carl simply wants to rescue Elizabeth. As more murders mount, Falkenberg enlists village lass ...

Jeff is an anguished man, who grieves and misses his young son that was killed by a driver in a car accident. He has become obsessed for revenge against the man and reckless with his wife and daughter. When Dr. Lynn Denlon, who has troubles with her marriage, is abducted by the deranged Jigsaw's apprentice Amanda, she is brought to a gruesome warehouse to keep John Kramer alive in spite of having a terminal brain tumor. Amanda puts a necklace gadget full of explosives around Dr. Lynn's neck connected to John Kramer's life support system, and tells her that if he dies the device will explode. Meanwhile, Jeff is submitted to a sick game of forgiveness with surprising dark consequences.

In a seemingly quiet town a mysterious meteor shower produces a sinister green meteorite that seems to have a dangerous effect on the dogs that who once were the kind well-behaved dogs we once knew turn into vicious killers and the residents are forced to engage in a battle of man vs beast as man's best friend turns into their worst enemy and one teenage girl named Roslyn has to fight her way through the vicious canines accompanied by her faithful dog shemp they must find a way to survive against the dogs they once called man's best friend