Ring by Koji Suzuki

In Japan, a mysterious videotape is making its rounds. It's said that if you watch the tape, you will receive a call telling you that you have seven days to live. Asakawa, a journalist, is perplexed by his niece's strange death. So perplexed that he decides to launch his own investigation in how his niece could have possibly died. However, his investigation will lead him on a journey darker than he imagined. Now he must figure out the mystery of the tape before its too late.