Richard Hendricks (Thomas Middleditch) is a shy, reclusive programmer who works at a large internet company called Hooli. He is also developing a music app called Pied Piper in a live-in startup business incubator run by entrepreneur Erlich Bachman (T. J. Miller). After a rocky post-TED elevator pitch of Pied Piper to venture capitalist Peter Gregory (Christopher Evan Welch), Hendricks also shows his work to a pair of programmers at Hooli who mock him. Within hours, however, Hooli executive Donald "Jared" Dunn (Zach Woods) and Gregory's assistant Monica (Amanda Crew) discover that the app contains a revolutionary data compression algorithm. Hooli CEO Gavin Belson (Matt Ross) proposes a US$4 million buy-out of Pied Piper, while Peter Gregory offers a $200,000 investment for 5% ownership in the company, an offer that would result in an equivalent valuation for the company. This leads Belson to increase his offer to $10 million. With encouragement from Monica and the support of Bachman, Hendricks chooses Gregory's offer. He hires the residents of the incubator, except for his friend Nelson "Big Head" Bighetti (Josh Brener), to become the Pied Piper team, along with Dunn, who defects from Hooli.

Hooli works to reverse engineer Pied Piper's algorithm based on the version he demoed, developing a copycat product called Nucleus. Gregory and Belson later each learn that Hendricks has been slated to present Pied Piper at TechCrunch Disrupt, a competition for unfunded startups. Belson is confounded by the news, and responds by scheduling the announcement of Nucleus at the event. Hendricks explains to Monica that he meant to withdraw from the competition, but Gregory demands that the company follow through, in large part due to his rivalry with Belson. The countdown to the event means that Pied Piper has to be ready to show in less than eight weeks rather than Gregory's initial plan of five months. The team rushes to produce a feature-rich cloud storage platform based on their compression technology.

At the TechCrunch event, Bachman takes the lead in a dramatic onstage presentation of Pied Piper. However the presentation is cut short when one of the judges assaults Bachman for having adulterous sex with both his current and ex-wives. Pied Piper automatically advances to the final round as recompense for the assault on Bachman. Belson presents Nucleus, which is integrated with all of Hooli's services and has compression performance equal to Pied Piper. Watching from the audience, the Pied Piper team generally admits defeat. The team eventually retires to a hotel room, where Bachman nihilistically suggests "jerking off" every member of the audience, and the group launches into an engineering conversation about how to do that efficiently. The discussion sparks a sudden revelation in Hendricks, who spends the entire night coding. The next morning, Hendricks takes the lead in making Pied Piper's final presentation. Having scrapped all of Pied Piper's other features overnight, Hendricks describes his new compression algorithm, and demonstrates it. Hendricks' algorithm strongly outperforms Nucleus and he is mobbed by eager investors.