Human Trials is the fifth episode of the second season of The 100. It is the eighteenth episode of the series overall.
Kane leads a mission to make peace with the Grounders. Meanwhile, Jasper agrees to participate in a risky experiment, Lincoln enters a world of pain and President Dante Wallace issues a warning. Finally, Finn's search for Clarke takes a violent turn.
In Mount Weather, Jasper meets with Dante Wallace about what happened to Clarke. Dante tells Jasper that Clarke ran away and offers Jasper the opportunity to go outside and look for her if he wants.
Kane and two Camp Jaha guards are in the forest, being led by a Grounder, Rivo, to his village. Kane stops to plant the "last tree" from the Ark. While stopped, Denby, one of the guards, tells Kane that Rivo refuses to drink. Kane convinces the Grounder to drink some water and tells him that they want to make peace with the Grounders.
Clarke wakes up after having been asleep for 10 hours and goes outside and sees Raven and they hug. Bellamy, Octavia, Monroe, and Mel return to Camp Jaha. Clarke runs to greet them, hugging Bellamy tightly. At first hesitant, he wraps her in an embrace. After, Clarke and Octavia hug. Bellamy tells her Finn is still out looking for her. Meanwhile, Finn and Murphy have found the Grounder village on Delano's map and are doing reconnaissance.
Lincoln is deep inside Mount Weather, strapped to a gurney. Cage approaches him with a syringe filled with a red liquid and tells him, "the first dose is the worst" after injecting him with the drug. Lincoln begins to convulse.
Abby, Sinclair, Byrne, and others discuss what to do about the kids in Mount Weather and the rest of the Ark Stations. Later, she tells Clarke that Murphy and Finn are not a priority and they're not going after them. Bellamy is outraged that Abby would just abandon them now that she has Clarke back and offers to go on his own instead. She refuses to allow it and Jackson pulls her away to deal with an emergency in Medical.
Clarke and Bellamy meet Raven at a section of the gate surrounding Camp Jaha. Octavia arrives and they gear up. Raven then has Wick shut down the electricity to that area of the fence and Bellamy, Octavia, and Clarke head out into the woods.
Jasper and Monty discuss going after Clarke when Maya Vie approaches. Monty starts packing while Jasper tells Maya he is too scared to go after Clarke. Suddenly, Maya's face starts breaking out in radiation burns and an alarm sounds a containment breach. They get Maya into Medical; however, seventy-five percent of her is covered in radiation blisters and the standard treatment is not working. Dr. Lorelei Tsing tells Jasper that in "theory," Sky People blood might heal Maya if they circulate Maya's blood through Jasper's system. Jasper agrees to do the procedure.
Bellamy is keeping watch in the woods while Clarke and Octavia sleep. Clarke wakes up and they discuss her closing the drop ship door with Bellamy telling her that it had to be done. He then tells her how Finn hasn't been the same since Clarke disappeared and he let Finn go with Murphy and two guns. Clarke tells him she was sure it had to be done, too. They discuss getting the Delinquents out of Mount Weather and Octavia wakes up and makes them include Lincoln in their mission.
Finn and Murphy sneak into the Grounder village at night and Finn lights their food supply on fire, causing the Grounders to be distracted as they try to put out the fire. While they sneak around the village, a Grounder stumbles upon them and calls out in warning. Murphy tells Finn they need to run but instead, Finn takes a Grounder hostage and begins shooting in the air as he asks who is in charge. Nyko steps up and tells them that their leader isn't there and they do not have the Delinquents either.
Cage returns to the room Lincoln is tied up in and gives Lincoln another dose of the Red drug, While the drug's onset wreaks havoc on Lincoln's system, Cage uses a tone generator and has Lincoln electrocuted at the same time. Lincoln collapses after fifteen seconds and Cage mentions that it is "nearly a record." He then orders Lincoln's dosage to be upped and to give shock treatments every two hours until Lincoln fears the tone generator - then they'll move onto Phase 2.
Jasper is in a bed in Medical next to Maya. Monty asks if Jasper is sure he wants to do this just as Maya starts seizing. Dr. Tsing says they need to begin immediately and Jasper agrees. Maya's blood is then circulated through Jasper. As Jasper grows sleepy from the drugs in Maya's system, Dr. Tsing mentions it is "perfectly normal," which causes Monty to grow suspicious. He asks how she knows that if she has never done it before. She clarifies that she meant it was "to be expected" and tries to send Monty away. Monty refuses to leave and takes a seat next to Jasper's bed.
Abby finds a note left by Clarke telling her that she and Bellamy were going after Finn and Murphy. She confronts Raven about helping them escape and Raven lies to her. Abby violently slaps Raven and tells her that Clarke is still "just a kid." Raven tells Abby that Clarke stopped being a kid the day Abby sent her down there to die.
As Kane, Rivo, and the Camp Jaha Guards approach the Grounder's village, Kane sends Denby and the other guard back to Camp Jaha in case it is a trap. He drops his weapons, as Rivo asks. Then he removes the Grounder's bonds as a sign of peace. As Rivo walks in front of Kane, he elbows him in the face and knocks him down before kicking him in the face and knocking him out. Kane is then dropped into a prison cell where he encounters Jaha.
Finn and Murphy have rounded up all the Grounders in the village into a pen. While Murphy stands guard, Finn runs around the village, searching for the Delinquents. He finds a stash of jackets and clothing that came from the dropship and is enraged. Finn runs over to the pen and demands to know where their friends are. Nyko tells him the only one he saw was Octavia but she was alone. Murphy tells Finn that they probably just found the gear. Finn slams a Grounder into the mud, pointing a gun at her head while Murphy begs Finn to stop. Finn steps back and releases the woman.
Octavia leads Bellamy and Clarke to the Abraham Lincoln statue near Lincoln's village. She breaks down and begins to cry as she tells Bellamy about how the Reapers took Lincoln and she couldn't save him. Bellamy attempts to comfort her by wrapping her in an embrace.
Cage enters Lincoln's room again and announces that Phase 1 is complete and it is time to start Phase 2. Another Grounder is wheeled into the room and a single dose of the Red drug is placed in between the two Grounders. Lincoln fights the other Grounder for the drug, ultimately killing him, and injects the Red drug into his neck.
Maya awakens in the Medical ward and Dr. Tsing explains how Jasper saved her life. Dr. Tsing leaves to talk to Cage as Jasper begins to throw up from the treatment. Cage and Dr. Tsing are confronted by Dante Wallace for using Jasper without getting any approval. Dr. Tsing asks for approval to move ahead with the rest of the 47 Delinquents and Dante dismisses her. He then asks Cage about the radiation leak that caused Maya's burns. Cage says there was a malfunction and tells Dante to use the 47 to get to the ground.
Murphy is trying to get Finn to leave the village and tells him that he cannot believe the man with one eye because Finn had a gun to his head. Nyko overhears and tells them they saw Delano, a man who was cast out of their village, and that this was his revenge. Murphy again tries to get Finn to leave when one of the Grounders flees the pen and Finn open fires on him. Artigas then leaps out of the pen and Finn guns him down, too. More and more Grounders start to panic as Nyko tries to keep everyone calm and Murphy tries to stop Finn from shooting but Finn keeps shooting. It is only when Clarke, Bellamy, and Octavia arrive and Finn sees Clarke that he stops shooting. Octavia rushes over to where Nyko is cradling Artigas' dead body as Clarke and Bellamy approach Finn. Finn says to Clarke, "I found you."
Murphy: "I got twenty-eight. These people don't look like warriors, Finn. And there's kids. Old people. There's nothing big enough here to hold our friends."
Bellamy: "The last time I saw you, you were closing the drop ship door. It had to be done."
Clarke: (silent before changing the subject) "Did you get any sleep?"
Bellamy: "It's okay. I'll sleep when we find Finn. You haven't seen him, Clarke. Losing you, the others, the war... it changed him. He executed the grounder that drew us the map. Pulled the trigger without even blinking and walked away."