The Orbital Sword: Nemesis Games by James S.A. Corey

Nemesis Games is a 2015 science fiction novel by James S. A. Corey, the pen name of Daniel Abraham and Ty Franck, and the fifth book in their The Expanse series. It is the sequel to Cibola Burn. Synopsis The Rocinante is down for long-term maintenance after the events of Cibola Burn. Three crew members decide to take care of some personal business during the down time. Amos Burton heads to Earth when he learns someone important from his past there has died, to pay his respects and to make sure no foul play was involved. Alex Kamal heads to Mars in the hopes of getting closure with his ex-wife and to see Bobbie while there. Naomi Nagata heads to Ceres station, when she receives a message that her son Filip is in trouble. While Jim Holden supervises repairs to the Rocinante, he is enlisted by Monica Stuart to investigate disappearing colony ships. Facing collapse by the exodus of colony ships through the rings, militant factions of the OPA coalesce into a Free Navy and simultaneously wreak havoc on Earth as they try to kill the Martian Prime Minister and Fred Johnson. Amos survives the attacks on Earth, to then free Clarissa Mao and escape back to Luna with her help and the help of Baltimore thugs from his old life. Alex meets up with Bobbie on Mars and together they investigate missing Martian military equipment and ships, which leads them into the middle of the attack on the Prime Minister's life. Naomi is kidnapped by her ex-lover Marco - leader of the Free Navy - but manages to escape; Alex and Bobbie rescue her. The crew reunites on the Rocinante. What's left of the Earth, Mars and the non-militant OPA government meet on Luna. Naomi finally tells Jim about her violent past. Amos asks that Clarissa stay as his apprentice. The Free Navy has encamped past the belt and is preventing anyone from going through the rings. Who is really behind the attacks, is it Marco? Or is it a renegade faction of the Martian military?