Clarke meets Cadogan and he says that she is the key because he assumes that she has the flame in her head.
He then remembers how the world was ending when he sent for his daughter Callie and his wife Gemma to meet him in the bunker with his son Reese. Callie is part of a protest group who doesn't see eye to eye with Bill, which continues when she finds out he won't let more people into the bunker when they have the space.
She tries to let more people in along with August, but it doesn't work. Bill also shows them that he stole a space ball but can't seem to make it work.
Two years later they see Becca coming down and bring her to the bunker. She wants to make everyone a nightblood so they aren't stuck under the ground, but Bill refuses. Because of the flame, Becca can hear and turn on the Anomaly Stone. She also manages to open a portal to what she calls Judgement Day.
She goes in and comes out terrified. She says they have to destory the stone because going there will bring about the end of the world. Bill refuses and wants her to tell him what she saw. Becca won't so he locks her up.
Callie tries to help her but Becca explains that they will burn her once Bill catches wind of her having a flame. She tells Callie how to use it and then gets burned to death.
Callie uses the nightblood that Becca brought to make as many people nightbloods as possible. She then challenges Reese and wins the flame by shooting him, only to then run away with the survivors so they can go above ground. Bill tries to stop them but Gemma saves the day. He then locks out Gemma with no nightblood and she has to rush to find Callie.
Reese is sent by his dad to track down the flame from Callie while Cadogan takes everyone who is left in the bunker into the stone towards Bardo.
Callie and August team up to find anyone they can who survived so they can turn them into a nightblood and so Callie could find the next person worthy of the flame.
Clarke plays along that she has the flame and that Callie is in it, but then threatens Bill for killing Bellamy. She wants to see Octavia, Diyoza, Echo (and Hope) but they are brought in clearly brainwashed to work with Cadogan. And Hope is nowhere to be found.