The episode unfolds with Octavia riding on a horse in the woods. She gets off the horse and hides behind a tree. Unexpectedly, we see Ilian walking through the woods and he approaches her horse. She jumps out and puts a knife to his throat. Ilian says that he can help her, but she wants no part of it. He says that he owes her for sparing his life, then lightning begins to strike and rain falls. Ilian refers to it as a strange rain, then Octavia orders him to get on the horse. They ride away.
In Arkadia, Kane welcomes Bellamy back. The acidic rain starts to pour heavily, as alarm rings throughout the camp, signaling everyone to run inside for cover. As Harper tried to run towards shelter, she shove one of the Arkadian citizens who tried to help her, causing him to fall to the ground and begin screaming in agony, as people push past him, not helping him up. Bellamy notices this and asks Kane to help him rescue the fallen citizen. They succeed in getting him inside. However, Bellamy wants to find Octavia, but Kane stops him. He reminds him that his sister is smart and can take care of herself. During their conversation, panic is growing inside their shelter. Everyone is stripping down and dousing themselves with water in order to get the burning rain off their bodies.
Back in the woods with Octavia and Ilian, they also strip down and start to drench themselves with fresh water. Octavia then tells Ilian to make a fire since he's clearly good at doing that.
At Becca's lab, we see Clarke arrive and meet with her mother. They begin to talk about how the hydrazine is the only shot they have. Abigail also tells Clarke that Raven is currently under sedation and that she needs to take it easy. She walks over to a microscope and begins looking at bone marrow. She then reveals to Clarke that injections with Luna's bone marrow can possibly give them Nightblood. However, they'll need a human test subject and they don't know who yet. During this, Emori overhears everything.
Back at Arkadia, Harper approaches Kane and blames herself for not helping the fallen citizen. He's currently not doing well and chances of him surviving are very slim. Kane then gets into a conversation with Bellamy. Bellamy decides to put on a protective suit and go out into the black rain. However, the suit is useless and Bellamy runs into a rover. He's talking to Kane and then decides to drive into the woods after hearing a distress call. Kane attempts to stop him, but it fails. Bellamy drives off into the black rain.
Meanwhile, Clarke and Emori are walking through the woods talking about black rain. She explains to Clarke that she's upset that everything is failing. Emori also tells Clarke that Skaikru is lucky to have her. They approach Becca's mansion where Murphy is listening to loud music. He is also cooking and shows Clarke that he's becoming a really good cook. Just as Clarke walks off to take a shower, Emori tells Murphy that they're leaving. She tells him that Skaikru is going to sacrifice a human in order to test a Nightblood solution. Emori feels that the sacrifice will be her. However, John tells her to calm down and that everything will be fine.
Seconds later, we see Clarke enter a bedroom and look at herself in the mirror. She then gets into the shower and cleans herself off. Following that, she lays in bed and closes her eyes. Suddenly, Clarke hears mysterious noises in the mansion. She grabs her gun to investigate and eventually enters an office. She lifts one of the blinds and notices a hole in the window. Murphy walks in and tells her not to be afraid, but Clarke warns that someone is in the mansion.
Suddenly, we see Emori taking food in the kitchen. A mysterious man attacks her, but Clarke and Murphy show up to deter him. Once they stop him, Emori begins to question him and wants to kill him. Murphy stops her from doing it, but Emori suddenly asks about where the "others" are. They decide to tie him up for questioning. However, Emori tells Clarke that once he's done talking, then she gets to kill him.
In the woods, we see Bellamy driving the rover while speaking with Mark and Peter on a two-way. Mark and Peter are the who the distress signal is coming from. As he's driving to rescue them, the rover gets stuck in mud, and he's unable to continue. On another two-way, Kane tells him that there's no way he'll be able to get to them. Bellamy informs Mark and Peter he can't get to them. Bellamy begins to beat the steering wheel in frustration.
Back at Becca's mansion, we see Clarke tending to Emori's minor wounds. Emori swears that she's going to get revenge on their prisoner for his crimes against her family. Clarke claims that she understands Emori's plight, but she doesn't believe her. She explains her banishment from her clan during her youth and Clarke admits that she doesn't understand that. However, she does understand that killing isn't the only way.
During their conversation, John Murphy is talking to the prisoner, but then Emori comes in and starts punching him in the face. Clarke wants her to stop because she'll kill him. She says, "What if his death can save us all?" It becomes clear who Clarke wants to volunteer as the Nightblood solution guinea pig.
Back in the woods with Octavia and Ilian, she continues to not speak to him. Ilian tries to carry on the conversation, but Octavia's focus is on sharpening her knife. Ilian begins to sadly reminisce about his responsibility for his family's death. He then wants to know Octavia's sad story, but she tells him to shut up. Despite her reluctance, Ilian feels that Octavia's previous demeanor before becoming a killer still exists. However, she tells him that he's wrong. She then proceeds to walk into the black rain, but Ilian stops her. She then kisses Ilian and tells him to make her feel something else. They proceed to make love and, for this moment, she's not thinking about Lincoln.
Moments later at Becca's lab, we see Abby walking around and her hand is shaking. She receives contact from Kane and he explains that the black rain is there. He says that they need a solution and she says that there may be a solution. However, in order to find it, she needs to do something that she doesn't really want to do. She asks Kane if she takes a life to find a cure, does it make her a murderer? Kane says that he doesn't know how to answer that. Suddenly, we see the fallen citizen from earlier is finally dead as Harper weeps over him.
Later on, we see Bellamy attempt to contact Mark and Steve. However, he receives no answer. Kane then tells him that he did what he could. Bellamy starts to lament about how he's failing everyone including Octavia. Kane reminds him that he did everything that he could for her as well. He says that Bellamy can't save someone that doesn't want to be saved. Additionally, his mother would be proud of the man that he became. Bellamy bitterly reminds Kane that he floated his mother.
Back at the cave with Octavia and Ilian, we see her wake up and realize that the storm is over. Ilian tells her that he's going home. She picks up a couple of curved daggers, then proceeds to drop them into a puddle. Octavia catches up to Ilian in the forest and tells him to get on the horse. She offers to take him home and he accepts.
Finally, back at Becca's lab, we see Abby inject the mansion prisoner. Abby puts the needle inside of him as Roan, Clarke and Jackson watch. Murphy and Emori also watch. She admits that the prisoner is not anyone that she knows. Her plan was simply to get someone else experimented on instead of her.