Barely arrived in Eiseberg, the capital, Frieren and his companions are apprehended by Sense, who needs Fern for a mission of the utmost importance: she and four other first-class men must protect Serie from an attempt to assassinate during the great ball organized to celebrate the foundation of the Empire! Land and Übel have already gone in recognition and infiltrated in a worldly evening to recover a precious document left by Lineal, the spy of the society of the wise men of the continent. Unfortunately, the magic secret services quickly detect their presence and launch themselves after them! Meanwhile, Frieren, patrolling with his protégés, feels a threat to her...