Simplify the following text for a Grade 7 native English-speaking person.
Original: The main plot follows the life of an average lazy stoner teenager , Anton Tobias ( portrayed by Sawa ) , whose hand becomes possessed and goes on a killing spree , even after being cut off from his arm .
Simplified: It follows the life of a teen whose hand becomes possessed and goes on a killing spree , even after being cut off from his arm .