Republic Commando: Triple Zero is the second book in the Republic Commando novel series written by Karen Traviss.
The novel starts with a flashback eight years before the Battle of Geonosis when Mandalorian soldier Kal Skirata goes to the rainy planet of Kamino to observe the the developing army for the Republic. He finds out that they are using clones from his friend, Jango Fett, and that the clones have had their age factor doubled; if they have lived a year, they will have aged two, and when they have lived two years they will have aged four years, etc. Skirata sees that the Kaminoans dealing with the some of clones are having trouble and wish to dispose of the mistakes. Before the unruly clones can be executed, Skirata protects them and takes it upon himself to train some of them.
Fastforwarding five days after the Battle of Geonosis. Skirata is on Coruscant and has just heard about the conflict and Jango Fett's death at the hand of Jedi Master Mace Windu.
The story line continues one year after the Battle of Geonosis. The Republic has learned that there are terrorists from the Separatists who have infiltrated Coruscant and are spying on the Republic. Skirata is hired by the Republic to track this threat down. He is joined by Omega Squad, consisting of three of Skirata's personally trained clone soldiers; Darman; Niner; and Fi, and a fourth member trained by Walon Vau; Atin. Helping them is an information broker from the Republic whose name is Besany Wennen. Also joining them is Jedi Master Arligan Zey, Jedi Knight Bardan Jusik and Jedi Knight Etain Tur-Mukan, who worked with Omega Squad during their mission to Qiilura. Skirata's Wookiee companion Enacca joins the mission, as well as Null ARC trooper Ordo, and a clone trooper named Corr. But things get more complicated as Vau and Delta Squad, consisting of Boss, Sev, Scorch, and Fixer, join in. Skirata and Vau have a rivalry because of their different methods of training clone soldiers; Skirata trained Omega Squad like a father figure and Vau trained Delta Squad through beatings. Atin has a hard history with Vau since he was beaten so many times. During the course of the story, Etain and Darman's relationship grows stronger. Etain becomes pregnant with Darman's child, but does not tell him.
During the mission to track the terrorists down, Jinart and Valaqil join in to remind Omega Squad and Etain that they still owe the Gurlanins a debt after they helped the clones and Jedi back on Qiilura. Etain and Omega Squad promise they will repay their debt eventually, but they ask the Gurlanins if they will help out in the mission. They agree.
The spies in the Republic are ultimately found, and the information they captured is destroyed and the terrorists are killed. Unfortunately, a rivalry between Omega and Delta Squad remains, and Atin and Vau get into a brutal fistfight that is quickly called off by Bardan Jusik. Later, after the celebration of the squads' victory over their mission, Etain reveals to Skirata that she is pregnant with Darman's child. Skirata is angered by this because he believes Etain used Darman. Nevertheless, the two agree to keep this a secret from everyone else, except from Jinart and Valaqil, and that the child will be a Mandalorian like his father, not a Jedi like his mother. Skirata promises Etain that she will be able to go to Qiilura and spend some time with Darman. Ordo figures out Etain is pregnant but decides to keep it a secret.