Selena plans to summon Reign with Coville's help.
M'yrnn says goodbye to Alex. He and J'onn plan to begin the Reach.
A hologram of Serena tells Kara, Alura, and Mon-El that Reign and Sam were separated, and only one will survive, but Reign isn't dead. Reign is the spark that will ignite catastrophes and turn Earth into a new Krypton. The hologram explodes.
Sam tells Alex that she doesn't feel well. Lena tells her that her blood cells are oxygen deprived and that they are reverting to Kryptonian. They decide to use the sun lamps to heal her.
Selena says they need the blood of Purity and Pestilence to make Reign whole. Coville says he knows where they can find it, the DEO.
The sun lamps don't work, but Lena plans to do some tests with the black rock.
Kara uses a crystal to contact Winn and warn him and Alex about Selena and Reign. They work to open a portal to bring them back, but the Dark Kryptonians attack before they can.
They go for the blood, but Alex fights them off while another DEO agent grabs it. He gets it to Kara, who has managed to get the portal open, but he dies in the process.
Kara gives the blood to Selena, but uses her heat vision to destroy it in her hand. Selena uses what's on her hand for the ritual. Alura mentions a fountain that could make Sam stronger, and therefore make Reign weaker. Sam is willing to take the risk despite her weakness.
Selena kills Coville after reviving Reign.
Sam goes into the Dark Valley as earthquakes begin to hit the city.
M'yrnn stops the Reach in order for he and J'onn to help save the planet.