Set a few months after the events of Trails from Zero, this role-playing adventure returns to the bustling city-state of Crossbell, a small but prosperous nation caught in a perpetual tug-of-war between two great powers, the Erebonian Empire and the Republic of Calvard. At its heart is the Special Support Section, a small police unit led by the earnest young detective Lloyd Bannings alongside his comrades Elie, Tio, and Randy, together with the girl KeA who has become like family to them. Reuniting and bolstered by new recruits, the team resumes its duty of protecting the people of Crossbell. Their work soon draws them into a tangle of danger, as they investigate the notorious Red Constellation mercenary corps, guard a tense international trade conference, and confront the shadowy secret society Ouroboros. Amid rising political turmoil and calls for Crossbell's independence, the SSS finds itself standing between the city and forces determined to reshape its fate.