After their high school graduation, six teens celebrate with a trip to the remote and mysterious Black Lake. Only Johnny seems to suspect there's something in the water stalking the revelers as they set out in their small wooden rowboat stocked with beer and fireworks. But why would Johnny let them go swimming if he knew what lurked beneath? A sudden attack from the depths followed by a lethal chain of events leave the teens stranded on the leaking vessel in the middle of the lake with no oars, no way back to shore, held hostage by a menace that circles them persistently. And so the teens turn on each other, and the petty high school grievances they almost left behind prove more deadly than the monster that waits to devour them.