In November 795 UC, Siegfried Kircheis arrives in the artificial resort satellite Kreuznach III for a vacation, as instructed by Reinhard von Müsel, who had to remain in the Imperial capital Odin to prepare for his receiving of the countship of Lohengramm. While he is checking in at a hotel, he saves an old man from a knife-wielding drug addict. The old man turns out to be Michael von Keyserling, a disgraced former Vice Admiral who was demoted and discharged from the military after his disastrous defeat in the Battle of Arlesheim on 792 UC. Kircheis then proceeds to the local police station, where he meets Superintendent Hoffmann, who implores him to assist the local police in a major thyoxin trafficking case which he believes is related to the seemingly random assault on Keyserling. Kircheis, having nothing constructive to do in Krueznach III, reluctantly agrees.
Prequel to the original series, focusing on Reinhard and his steps up the chain of command in the Galactic Empire. Also focusing on the FPA's Yang Wen-li. A chronicle on how he earned the title "The Hero of El Facile" and his handling of assignments he received after the historic event. Spiral Labyrinth also continues with the background of Reinhard and Kircheis where the first Gaiden left off.
