The Isaac Quadrant lies in the Enigma Sector and consists of the Bradbury, Enigma, Ghorah Khar, Gwynedd, Harrison, K'arakh, K'tithrak Mang, Niven, Racene, Repleetah, Rigel, Shelton, Telamon, Tesla, Trk'Harna and Zelanzy systems.
The Isaac Quadrant consists of a large series of colonies, of which most belong to the Terran Confederation. However, several also belong to the Union of Border Worlds and the Kilrathi Empire. The sector capital, Enigma (planet), is located in this quadrant.
The Isaac Quadrant saw much action during the Terran-Kilrathi War, and was the center of Kilrathi military actions during the Enigma Sector Campaign. There base of operations was the Sector Command HQ at K'tithrak Mang. The various colonies in this quadrant changed allegiances several times throughout the campaign.
The Isaac Quadrant is home to Repleetah, where the bloody but strategically-worthless Battle of Repleetah took place for over ten years before the battle ended in a stalemate. It is also home to the Kilrathi colony of Ghorah Khar, which was the center of a separatist movement against the Kilrathi Empire that lasted for over a decade. Finally, the Gwynedd System was home to Caernarvon Station, where illustrious pilot Christopher Blair was once stationed.
In 2656, the famed TCS Tiger's Claw attempted to destroy the Kilrathi Sector Command HQ at K'tithrak Mang in an attempt to liberate the sector. This attempt ended in failure when Kilrathi stealth fighters destroyed the Claw. Colonel Blair, one of its pilots, was charged with negligence for not saving the Claw when in reality he did everything he could to save the vessel. He was forced to serve for In-System Security at Gwynedd for ten years, away from the frontlines. In 2665, he rejoined the War after saving the TCS Concordia in Gwynedd, and took part in a brutal campaign that ultimately saw the fall of K'tithrak Mang and the liberation of the sector.
In 2673, during the bloody Border Worlds Conflict, the Isaac Quadrant was the site of the horrific Telamon genocide, which saw the extermination of 90% of Telamon's population at the hands of the elusive Black Lance. The tragedy at Telamon would see the Black Lance's leader, Space Marshal Geoffrey Tolwyn, convicted of war crimes and ultimately his suicide later that year.