Clarke teams with an unlikely ally after making a horrific discovery about Mount Weather’s medical ward. Abby confesses to a crime.

A suspicious Clarke confronts President Dante Wallace and demands answers. Kane interrogates one of the 100, and Abby performs emergency surgery.

Trapped in the white room, Clarke tries to make sense of her surroundings. The Ark survivors face moral and physical dilemmas. An old enemy returns.

As the conflict escalates, Clarke pleads with Bellamy to do the right thing. Octavia makes a difficult choice. Raven and Jasper work against time.

Clarke and Finn are confronted by a new enemy, Bellamy makes a heroic move to save Jasper, while those on the Ark face the inevitable.