Sirantha Jax is an elite jumper. She possess a unique genetic structure which enhances her ability to lead a jump through grimspace. She has quit her position as a diplomat, a job for which she was totally unsuited. She and March plan to stay out of the scramble to rebuild the political structure of the Conglomerate.

They travel to the far reaches of the universe to a station which houses friends that they had to leave behind. On the way, they encounter a ship carrying slaves which is attacking another ship. Sirantha has learned compassion through her connection with March. Even as they destroy the ship, she cannot leave the slaves to die. The rescue nearly kills her.

The slaver was full of children, which they take to the Station. They will search for the children's parents but receive an unexpected offer from the head of the Conglomerate. They are asked to form an alliance of ships to fight the Morgut. The Morgut are invading, and no one has ever been able to stop them. They kill everyone without compunction as they search for colonies for their species.

March and Sirantha contact the privateers they once fought against to cobble together a militia. Their time is spent training and drilling to become a force to be reckoned with. As the Morgut begin invading, Sirantha and March will take to space while putting their relationship on hold. March can't afford to show any favoritism. Sirantha even goes so far as to contact her mother, who leads the criminal elements to help the fight against the Morgut.

As the battles progress, they encounter the Morgut in numbers that shock even the most battle scarred veterans. When they encounter the Red Cloud, it will be an all out battle which will result in a huge loss of life. Sirantha's mother will shock them all with her final action. As they rest in her mother's home, Sirantha comes to the realization that there is only one thing that can save her people. It may require the ultimate sacrifice but, given what everyone else has suffered, can she do any less.

Fraught with action, farewells, and sorrow, fans of this series won't be able to put KILLBOX down. We see the action from the point of view of the characters, as well as some of the political decisions required by the leaders as they face the battle for their lives. Ms. Aguirre has left the reader hanging with a finish that guarantees the reader will be on pins and needles waiting for the next installment.