Clarke wants answers from the President. Abby performs emergency surgery. Octavia will do anything to find Lincoln.

After discovering a horrifying project in Mount Weather's medical ward, Clarke joins forces with an unexpected ally.

Clarke ends up being betrayed by somebody that she trusted. Bellamy, Finn and Murphy attempt to save a stranger.

Kane takes part in a mission to make peace with the Grounders. Jasper decides to take part in a risky experiment. Lincoln enters a world of pain and President Dante Wallace issues a warning.

Tensions are running high between Clarke and Finn. Raven finds out that Mount Weather is interfering with their communication systems.

Bellamy is able to get Clarke to agree to accompany him to the drop ship. Dr. Tsing is in charge of a deadly experiment.

Clarke comes back to Camp Jaha with some shocking news. Finn has to face the consequences of his actions.

Lives are left in danger following the arrival of a new threat. Lincoln and Bellamy decide to break into Mount Weather.