On the Roci, Holden apologises to Naomi for getting so obsessed with destroying the protomolecule that he put everyone at risk. Naomi, determined to have no more secrets between them, tells Holden that she didn't actually destroy their sample of protomolecule. Not only that, she believed that, as both Mars and- she thinks- Earth have protomolecule samples, it was necessary for the Belters to also have one, to maintain a balance of power. To this end, when she feared that she was going to die on the relief ship, Naomi contacted Fred Johnson and gave him the coordinates of where she hid the missile containing the sample. He now has it.
We also finally see Dr. Strickland: he's putting Mei- thankfully very much still alive- in a stasis pod and storing it somewhere with a lot of other ones, presumably also containing kids. This guy needs to go down.