Someone has discovered a tactical nuclear device in Fukuoka's Kyūshū Telecom Tower, and some 35 million citizens are subsequently evacuated over a five-day period to allow the Ground Self Defense Force to safely defuse and remove the device. It is assumed that the culprits behind the bomb are militant refugees, but Section 9 thinks otherwise, and with the Prime Minister's permission, they enter the hot zone to investigate the bomb firsthand. Borma and Paz are sent to inspect the bomb itself, which appears to be a dirty bomb, but upon closer inspection, Borma deduces the device had elements of an implosion bomb which uses American explosives...