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.

Amos Burton heads to Earth when he learns his parent figure there has died, both to pay his formal respects, and to make sure no foul play was involved.

Naomi Nagata heads to Ceres station when she receives a message from her former lover Marco Inaros, although she doesn't tell any of her crew-mates why she is leaving.

Alex's ex-wife rebuffs his attempts to reconnect, and he instead finds himself working with Bobbie Draper, who takes advantage of his presence to try to investigate missing Martian warships.

After they're attacked and nearly killed by an unknown group, they take the Razorback, still in Bobbie's possession after the events of Caliban's War, to investigate the asteroid coordinates Holden sent, where they stumble upon a large fleet of stolen Martian ships.

Naomi spent her youth involved with his radical OPA cell, but left after he tricked her into coding a software override on ship reactors that he used to kill hundreds of Earthers.

Under heavy fire from fake reinforcements that were really Free Navy ships, the Martian prime minister flees on the Razorback with Alex and Bobby towards Luna.

His plan foiled, Marco instead sends out a ship rigged to explode when the Rocinante gets close, luring Holden with a fake distress call using Naomi's voice.

At the book's end, it is revealed that the Free Navy's creation was orchestrated by a rogue faction of the Martian government led by Admiral Winston Duarte with the purpose of trapping Earth and the Belt in a war.