An unidentified man posts a live feed on social media showing that he has kidnapped two strangers and intends to kill one before the day is out. His intention is to hold a capital 'trial' online. As the authorities recognize what's happening, it becomes apparent that the online public is going to act as judge and jury.

When an unidentified hiker is found deceased in the Florida wilderness, authorities release a sketch. Multiple hikers call in claiming to have met the man. There's only one problem – he never told them his name. It would take two years, thousands of devoted internet sleuths, and a miracle of science to identify him, and that's when the trouble really starts.