We spend time with Octavia right after she goes into the Anomaly and comes out on Planet Beta. Turns out she got there three months after Diyoza, and from there she helps her give brith to Hope. They raise Hope together but Octavia spends six years trying to get back to Bellamy. She tries everything but eventually Diyoza tells her if she leaves then she will leave Hope alone if something happens to Diyoza. So Octavia writes Bellamy a note to throw into what she assumes is the way back to Sanctum in the water, and stays with Diyoza and Hope.
But one night the disciples arrive, because the letter actually reached them in Bardo. They don't know about Hope, so Octavia hides her and she and DIyoza end up taken. Hope ends up alone on Skyring.
In present time, Hope arrives with Echo and Gabriel back to her Skyring home. She remembers everything again and she thinks she can get them to Bardo. But the code there is washed away, so they have to find another way. There is a strange man now living in Hope's home who is called Orlando. They track him because Hope says they will need him.
They end up at a cemetary that he built and there Gabriel realizes that Eligius 3 was there. He takes one of their mind drives and ends up watching one of the dead people's memories. But before he can save the code to use the Anomaly stone to get to Bardo, Orlando destroys the memory reader.
Hope says though that Orlando is their key out of there and they have another five years on Skyring to go.