"Fortune's Pawn" by Rachel Bach http://www.amazon.com/Fortunes-Pawn-Paradox-Book-1/dp/0316221112, the first book in her "Paradox Trilogy" was hands down the best science fiction hit of 2013. If you read just one sf book in 2013, this should have been it. A fun action packed space opera. It starred Devi Morris, an armor clad mercenary warrior who fought and killed space aliens. "Honor's Knight" http://www.amazon.com/Honors-Knight-Paradox-Rachel-Bach/dp/0316221082/ref=la_B00DVP4034_1_1?s=books&ie=UTF8&qid=1396023562&sr=1-1, Bach's followup is equally ferocious, but contains more politics and background story. While less intense than the first book, Bach definitely sustains the high action content and keeps the story moving along. Its a very good read.
Devi Morris is a trained mercenary stationed aboard The Glorious Fool, a special ship captained by Brian Caldswell. She is one ferocious warrior who kicks butt and takes no prisoners. But Devi has lost her memory and cannot remember everything that happened in the last 6 months. We do know the following.
Caldswell has been secretly stealing young girls and converting them into clones of Maat, a powerful user of phalaanx energy who can battle the phantoms -- inter-dimensional space aliens. The phantoms are so powerful that they can destroy whole planets. For seventy years, Caldwell has been on the front lines trying to secretly contain and thwart the phantoms. But the situation is unstable. Bennent, Caldwell's ex-partner is leading a rebellion against Caldswell.
Meanwhile the powerful alien and murderous clan of Xith'cal, who breed humans for food, developed a virus that was intended to fight the phantoms. But the virus is inimical to Xith'cal and when it breached containment, all the Xith'cal on that ship died. But someone did get infected and is still alive.
Caldwell wiped Devi's memory at the end of Fortune's Pawn because she got too close to the truth of the mission. But she also has a secret. Black soot is spreading over her body when she gets angry. It gives her special powers to see the space aliens. Her new abilities have attracted the attention of the Xith'cal, Caldswell's enemies and the Leglis, who also are inter-dimensional space aliens. It was the Leglis who made a treaty with Caldswell 70 years before to imprison Maat and to help him fight the phantoms.
In this action packed sequel Devi must learn to use her new found powers to see and hunt phantoms. The Glorius Fool and its crew are once again battling the phantoms, the Xith'cal, who want to control Devi, Bennett and his allies and even Maat to save the universe. Its full of action, space battles, some pathos, more action and individual man-alien warfare. Caldswell, Bennett, Caldswell sister and law, and even the cook on the Glorious Fool can shapes change into super soldier aliens. There are more close encounters with the Leglis and Xith'cal.
A minor quibble is that the book dives right into the action and without an introduction to the prior book, it places a large burden on the reader to come to grips with all of the characters. Bach would have been better off adding a few paragraphs of introduction.