Erkin, a young pharmacist hailing from the war-torn north, rises to prominence in the Kingdom of Mormeratta. Unexpectedly called upon to heal a reclusive figure known as the 'master of the castle,' Erkin grapples with his limited understanding of the illness and the enigmatic patient. Driven by a desire to avenge his parents' death at the hands of the Witch of the Sun, Erkin reluctantly agrees, unaware that his path to revenge may intertwine with a surprising revelation. As he delves deeper, Erkin faces a moral dilemma when his sworn foe transforms into an unexpected ally. Will Erkin choose justice or forgiveness when confronted with this newfound connection?