After the pivotal Battle of New York in 2012, Adrian Toomes and his salvage firm are contracted to clean up the city. However, their responsibilities are swiftly overtaken by the Department of Damage Control (DODC), a collaborative effort between Tony Stark and the United States government. This turns into a source of frustration for Toomes, who clandestinely holds onto Chitauri technology they have collected in order to develop cutting-edge weapons, notably an imposing Vulture suit.

Fast forward eight years later, Peter Parker becomes part of the Avengers, but Stark advises him to prioritize his studies. Parker makes the decision to leave the academic decathlon in order to dedicate more time to combatting crime as Spider-Man. His closest confidant, Ned, unexpectedly discovers his secret identity.

During a mission, Parker confronts Toomes' accomplices, Jackson Brice (also known as Shocker) and Herman Schultz, as they attempt to sell weapons to a notorious criminal. Stark comes to Parker's rescue after Toomes accidentally causes Brice's demise, resulting in Schultz taking up the mantle as the new Shocker.

Parker and Ned stumble upon a perilous weapon left behind by Brice, leading them to track Schultz to Maryland. Meanwhile, Parker rejoins the decathlon team for a class trip to Washington, D.C., but his plans are thwarted when he gets caught in the act of trying to thwart Toomes from pilfering DODC weaponry.

In the face of danger, Parker heroically saves his friends from a Chitauri grenade explosion at the Washington Monument. Subsequently, he also prevents a catastrophe by rescuing passengers on a ferry that is dangerously ripped apart by Toomes' malfunctioning weapon. However, Stark confiscates Parker's suit as a consequence.

Returning to his high school life, Parker musters the courage to invite his crush, Liz, to the homecoming dance. Much to his shock, Parker discovers that Liz's father is none other than Toomes himself, who has become privy to Parker's alter ego. With Toomes planning to hijack a DODC plane, Parker is compelled to don his homemade Spider-Man suit and intervene.