A disgraced military intelligence officer becomes the target of a vengeful former soldier, leading him into a conspiracy of loyalty and murder on the lawless fringe of the Astragius Galaxy.

The story follows Keik Karadyne, an intelligence officer whose career was destroyed by his involvement in the Plambandool Scandal. Before the events of that scandal, Keik is assigned to a facility in a rain-soaked, decaying city when he learns that a dangerous man has escaped from a military prison. The escapee is Berak, a former captain with the call sign Black Wolf of Parmis, who commanded a mechanized unit in the Rodengulf Armored Division of the 18th Melkian Army. Branded a war criminal for his brutal actions, Berak blames Keik for his prosecution and imprisonment and now seeks revenge.

The situation becomes more complicated with the arrival of Somilia Berak, the fugitives sister. She approaches Keik with an unusual and chilling request: to kill her own brother. Having lost his sanity, Berak now poses a deadly threat to everything around him, and Somilia believes assassination is the only way to stop him. As Keik pursues the rogue officer through the citys underworld, he must navigate a labyrinth of betrayal and violence where the line between hunter and prey constantly shifts.

Published in 1993, Defenseless City serves as a spin-off to the Armored Trooper Votoms franchise, specifically functioning as a prequel to the 1988 original video animation series Armor Hunter Merowlink. The narrative adopts a hardboiled detective tone, focusing on human conflict and psychological tension within the franchise's gritty, post-war science fiction setting. While grounded in the world of giant Armored Troopers, the story emphasizes character-driven drama and the moral ambiguities of a society struggling to move past a devastating interstellar conflict.