Rachel Keller (NAOMI WATTS) is a reporter for the Seattle P.I. who's raising her young son, Aidan (DAVID DORFMAN), by herself. That's become a bit trickier of recent due to his obsession with death following the untimely demise of his 16-year-old cousin, Katie (AMBER TAMBLYN).
It seems that the teen had previously watched a bizarre videotape that somehow causes the death of anyone who watches it. That occurs exactly seven days after the fact, and now Katie, her boyfriend and two others are dead after doing so. Rachel can't believe that's possible, but starts investigating the story and hears that others know of this urban legend and the fatalistic phone call one receives after watching the tape.
Her curiosity eventually gets the better of her and she ends up watching the tape that is a collection of bizarre and creepy images and imagery. Not believing the legend, she then shows the tape to her friend,
Noah (MARTIN HENDERSON), who's similarly skeptical of the tape's lethal capabilities.
Soon, however, enough bizarre events occur that the two begin to wonder if it may be true. Accordingly, they set out to investigate the tape based on its visible and partially discernible content. That eventually leads them to Moesko Island and the former horse farm of Richard Morgan (BRIAN COX) where they come to believe the ghost of a young girl, Samara (DAVEIGH CHASE), is somehow involved in the deaths and other spooky occurrences.
With time increasingly running out, Rachel and Noah race to solve the mystery and figure out if there's a way to avoid being killed.