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.

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.

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

Lexa and Clarke manage to make a deal.The newly created alliance is under threat. Monty comes up with a plan.

Clarke begins to question Lexa's leadership decisions and Indra continues to push Octavia. Meanwhile, at Mount Weather, Jasper steps up into the role of leader, and Cage throws Maya into a life threatening situation.