Earth continues to deteriorate with an estimated 15 billion casualties from both the initial blasts and the mass starvation from lack of sunlight. The Earth fleet is unable to engage the Free Navies because they are continuing to throw rocks at Earth. The Free Navy controls the Slow Zone with the station and some rail gun defenses. The fleet has to stay and destroy the rocks before they are able to hit Earth again. Earth hires the Rocinante to go out and destroy or capture the ship that is throwing rocks at Earth. They sneak up on the other ship and are able to capture the ship and two crew members. As a result the Earth fleet is freed up to engage the Free Navy.
Marco makes plans to evacuate Eros as the Earth/Mars coalition move to retake the asteroid. Marco intends on evading the Free Navy instead of trying to engage them in a major fight. He also tells Pa to stop giving Belters the supplies they were stealing from the captured Colony ships. Pa as a result rebels from the Free Navy and starts using the ships loyal to her to give the food and supplies back to the Belters who need it. Pa and Marco run a few minor skirmishes against each other. She eventually allies with the remains of the OPA and Fred Johnson and uses Tycho Station as a base of operations to get supplies out. Later Fred Johnson tries to get a meeting together on Tycho between the remaining members of the OPA. Oh the way there the Rocinante is ambushed by the Free Navy. The Rocinante manages to escape after destroying one ship and disabling another, but Fred Johnson died from a stroke during a high-g burn.
While Ganymede was officially neutral, The Free Navy began occupying the base and using it as a staging area. Prax was working a new strain of food based on the Protomolecule that could help Earth with it's mass starvation problem. One of his co-workers tried to send the forumla to Earth and was found killed by the Free Navy operatives on the station. Later he covertly sends the formula to Earth. Eventually he is found out, but he claims to have accidentally put it where anyone could grab it and someone else had actually sent it to Earth. Prax is believed as released from custody. The Earth begins using the new strain of food and mass producing it to save a lot of people from starving to death.
Holden has to go in place of Fred Johnson. He is able to convince the various leaders with Dawes help to support the Earth/Mars coalition in a joint venture to attack the Free Navy. Holden is going to fly with the Rocinante and an old ice hauler with thousands of small ships loaded with OPA fighters to retake the Slow Zone. The rest of the coalition fleet runs a massive coordinated assualt on all Free Navy strongholds as a distraction. The Rocinante is able to get to slow zone and capture the station, but the rail gun defenses are destroyed instead of captured. Marco and a dozen other ships head towards the Slow Zone to retake the station. Filip, Marco's and Naomi's son, decides to abandon the cause and stays behind before they leave. Naomi is able to figure out why ships keep disappearing when going through the gates by using the station's logs of all of the traffic. She discovers that under certain conditions the next ships to go through are destroyed. She times the ice hauler they brought to go through right before the enemy fleet does, and all of the enemy ships disappear as a result.
With Marco gone, the Free Navy quickly folds. In the aftermath, Holden comes up with a plan to keep the Belters relavent in the new world order of having thousands of habitable planets. The OPA is turned into a guild with exclusive control of the Slow Zone, and therefore all inter-system travel and trade. Pa is put in as the first president of the guild. As a result everyone is able to find a semblance of peace while Earth recovers and all of the new planets begin to be colonized.