Following the establishment of peace by the Interstellar Alliance, the prestigious Cosmo Academy was founded, offering its graduates unlimited career opportunities. To secure a spot at this exclusive institution, candidates must excel in the triennial entrance exams, a fiercely competitive ordeal. Lane Tadatos, a determined Terran, advances to the final exam stage, where he and nine others are transported to the Esperanza, a stranded spaceship. Tasked with enduring 53 days isolated on the vessel, with only an emergency button for communication, the examinees face a daunting challenge. Their trial takes a treacherous turn when a headcount reveals an extra member among them, pointing to an imposter hidden within their midst.