Invincible (The Lost Fleet Beyond the Frontier)
by Jack Campbell
This is the second book in the Lost Fleet series that follows the adventures of Black Jack Geary. This novel begins with Jack and the fleet arriving in the Sutrah system. As their detection systems come on line, they detect two enemy warships. During a meeting after the incident, Geary is indirectly accused of cowardice because of the incident by officers who resent his command of the fleet. As the Allied Fleet is planning to raid the system for resources, it is discovered that there is a prison colony on one of the planets containing Alliance prisoners of war. Upon liberating the POWs, it is discovered that among them is a former hero of the Alliance, Captain Falco, who believes he and not Geary should command the fleet, and who has secret allies among the officers under Geary's command.