"Light Yagami is a brilliant, but bored, high school student who resents the crime and corruption in the world. His life undergoes a drastic change when he discovers a mysterious notebook, known as the "Death Note", lying on the ground in the year 2003. The Death Note's instructions claim that if a human's name is written within it that person shall die. Light is initially skeptical of the Death Note's authenticity, believing it is just a prank. However, after experimenting with it and killing two criminals, Light is forced to admit that the Death Note is real. After meeting with the previous owner of the Death Note, a Shinigami named Ryuk, Light seeks to become "the God of the new world" by passing his judgment on criminals."
From the Wikipedia article.
Death Note - Wikipedia, the free encyclopedia