If you are rewatching for the plot, these are the most critical: 1x01 - Pilot: Sets up the premise and characters. 1x11 - Red John's Friends: Deepens the personal stakes for Jane. 1x23 - Red John's Footsteps: Concludes the season with a high-stakes Red John encounter.
Notice the index doesn’t list a Season 1 Episode 24. That’s right—23 episodes. In an era of 22-episode seasons, The Mentalist gave us one extra hour of tension. The finale index entry reads simply: "Jane finally gets a lead on Red John. A CBI agent is murdered." index of the mentalist season 1 install