The scene where Will Byers is found or connected to new information occurs in several episodes across the series, but the pivotal moment that defines his reveal is the first season finale, and related developments appear in later seasons as well. If you’re asking about the moment Will is found or officially identified as alive after his disappearance, that happens in Season 1, Episode 1, titled “Chapter One: The Vanishing of Will Byers.” He subsequently reappears in Season 1, Episode 3, “Chapter Three: Holly, Jolly,” and much of the earlySeason 2 arc centers on his ongoing experiences in the Upside Down and his return to Hawkins. If you meant a particular discovery about Will in a later episode (such as how his imprisonment in the Upside Down is interpreted, or a reveal in Season 5’s setup), please specify which moment or season you have in mind, and I can point to the exact episode.

• Will’s initial disappearance and discovery of his absence: Season 1, Episode 1.
• Will’s return and reintroduction, with hints of his time in the Upside Down: Season 1, Episode 3.
• Major revelations about Will’s experiences and the Mind Flayer influence: Season 2, notably episodes around Will’s visions and the mind control arc.
• Season 5 details about Will’s fate and past events: as of the latest updates, Season 5 continues the arc and adds new context to Will’s Journey.