"Chuck Versus the Truth" (Season 1, Episode 8), airing on November 12, 2007, is a pivotal episode wherein the main characters are exposed to a lethal truth serum. The episode features the introduction of Lou (Rachel Bilson) and forces Chuck and Sarah to confront their feelings for each other. For a detailed plot recap, visit TV Tropes . "Chuck" Chuck Versus the Truth (TV Episode 2007) - IMDb
