5 essential episodes to watch before the season 5 premiere of The 100

Season 4, Episode 1: “Echoes”

From the very beginning, The 100 sets itself apart by its commitment to its premise. Its characters have always had to contend with an “apocalypse” of sorts, or, at least, the ending of a world. When the series kicked off, 100 teenaged criminals were sent to Earth from a space station that they believed housed the last remaining humans following a nuclear apocalypse on the planet. In the ensuing seasons, the 100 have fought to survive, and in the season 3 finale, were tasked to destroy an artificial intelligence called A.L.I.E., alongside those under the AI’s control. Alas, A.L.I.E. predicted a new apocalypse that will plague the Earth once more, spelling death for everyone on the planet.

Now, in the season 4 premiere, Clarke must attempt to help her people, as well as everyone else on location, move forward in the wake of A.L.I.E.’s destruction and face the prophecy of another apocalypse hanging over their heads.

Raven Reyes (Lindsey Morgan) — who, by the way, is a handicapped badass — discovered that the Earth’s radiation levels were rising, and that the purpose for A.L.I.E.’s construction was to protect the remainder of the Earth-based population from some two dozen nuclear reactors due to expire. Uh-oh is right.