Recap / The 100 S 04 E 01

• Appeal to Force: A member of the council tries to enforce law in Polis after the death of Ontari from the previous season. Echo proceeds to slit the council members throat and makes it clear the Ice Nation are the ones in charge.
• The Bus Came Back:
  • Echo, who disappeared after "Ye Who Enter Here", is back and preceded to take control of Polis for the Ice Nation's sake.
  • Roan whose fate was unknown from the previous season is revealed to be alive (though just barely) at the beginning of this episode.
• Driven to Suicide: Jasper, after the events of the previous season, comes very close to committing suicide. After finding out about the reactors melting down, he decides that he doesn't need to.
• Let's Split Up, Gang!: Clarke and Bellamy return to Arkadia in order to find a way to stop the nuclear reactors. Meanwhile Kane, Abby and Octavia stay in Polis in order to ensure that Roan stays true to their alliance.
• Monumental Damage: The Stinger of the episode shows the Pyramids of Egypt being destroyed by a wave of radiation in order to show just how devastating this new threat is and how little time Clarke and co have to stop it.
• Noodle Incident: Raven mentions that there was a second Fukushima disaster a few years before the world was nuked.
• Reasonable Authority Figure: Roan who, while naturally suspicious of Clarke and the rest of the Sky People, also listens to what she has to say about the radiation and ultimately spares her life in order to save the world from Nuclear Devastation.