In this episode, the threat of ALIE spreads to Polis, forcing characters to make impossible choices between submission and physical suffering. Meanwhile, Clarke’s group searches for the elusive Luna, hoping she is the key to stopping the AI. 1. The Fall of Polis

For more detailed analysis, you can read expert reviews on Den of Geek or Telltale TV . The 100 Review: Join or Die (Season 3 Episode 13)

: Even when a destination looks like a "dead end," look for environmental triggers (like the signal fire) to proceed.

: Clarke, Bellamy, Octavia, and Jasper follow Lincoln’s map to find Luna, a Nightblood who can host ALIE 2.0 and stop the first AI.

This guide covers the core plot lines and survival stakes of the 13th episode of Season 3 of The 100 . Overview

: The group reaches the coast but finds only rocks. Jasper accidentally discovers that green fire is the signal needed to summon Luna’s people.

: While imprisoned, Murphy gains critical information that may help him survive the chaos. 2. The Search for Luna

: After signaling, they are attacked by Grounders emerging from the sea. These "underwater" Grounders offer them "safe passage" via a sedative, which Octavia and Jasper take to meet Luna. 3. Flashbacks: The Ark