Siegfried Kircheis is introduced by Michael von Keyserling to his old friend Christopher von Basel, a retired Vice Admiral. Kircheis notes that Basel continues to claim that he and his wife have only just arrived instead of the day before as revealed by Superintendent Hoffmann. Later the day while alone in a café, Kircheis finds a suspicious-looking man and begins to tail him. The man turns out to be a bait to trap Kircheis inside a flying ball court, where he faces five knife-wielding assailants. Kircheis holds off long enough before Hoffmann leads the local police to intervene. One of the assailants tries to escape and takes a civilian hostage, but is stopped by Kircheis. Hoffmann then reveals to Kircheis that Keyserling's would-be assailant used to be in a supply unit in the Keyserling Fleet and that unit was headed by the then Rear Admiral Basel. He then speculates that Basel might have planned the attack on his old friend due to a dispute over the thyoxin trafficking operation. Kircheis, wishing to learn about Keyserling's side of the story, requests Hoffmann to give him some time to investigate privately. Kircheis then confronts Keyserling, who admits of covering Basel's involvement in thyoxin trafficking for the sake of Basel's wife, Johanna von Basel, who he loved greatly.
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.
