Kurt Kunkle, fueled by an insatiable hunger for online fame, embarks on a twisted social media experiment. He rigs his rideshare vehicle with cameras, christening his livestream "The Lesson," a dark tutorial on achieving viral status. His initial attempts at garnering attention are pathetic, a stark contrast to the online success of his former babysitting charge, Bobby. Driven by jealousy, Kurt escalates his tactics, poisoning unsuspecting passengers with laced water bottles, broadcasting their deaths to a dwindling audience. Jessie Adams, a comedian with a substantial following, becomes a fleeting passenger, her genuine disdain for Kurt's desperate antics fueling his rage. The escalating violence, including the brutal murder of Bobby, finally starts to draw attention, but not the kind Kurt craves. His father, Kris, a washed-up performer, offers a glimmer of hope with the promise of a celebrity tag, leading to a botched attempt at social media validation that ends in further bloodshed.

As the "Rideshare Killer" gains notoriety, the Spree app temporarily shuts down, and Jessie, after a cathartic onstage rant against social media obsession, finds herself trapped in Kurt's deranged game.