Though technically the finale (spanning episodes 21 and 22), the season 4 conclusion involves a massive secret being revealed.
Season 4, Episode 21 is It features a major resignation and a high-stakes investigation. [S4E21] The Last Word
You can find a detailed review and analysis of its political relevance on Star Trek Forever or read about its iconic civil liberties speech . The West Wing Though technically the finale (spanning episodes 21 and
Entertainment Weekly provides a recap of "Mr. Kaplan: Conclusion," which centers on the "truth" Red is hiding. Other Notable S4E21 Episodes detailed on Wikipedia .
: "Career Day." A lighter episode involving Claire returning to the workforce, detailed on Wikipedia .