Watch The Substitute (2026) series free. Depicts the story of a high-achieving, low-income student who takes the College Scholastic Ability Test (CSAT) for another person to avoid blackmail. Children are placed on an exam stage where they risk falling behind in life if they do not complete the CSAT safely. To obtain the "score" that will determine their future, a survival CSAT war unfolds thrillingly with betrayals and tricks everywhere. It is expected to expose the dark side of entrance exams unflinchingly through the "unfair" children who search for the correct answer amid extreme dilemmas. Kang Geon Tae, the miracle of a "special low-income scholarship student" who does not lose the top rank at Jeonggyeong High, where wealthy people abound. He drew a perfect blueprint toward the first cornerstone of life, the "prestigious university," but the choices he made to survive return as the only stain. He is a figure who falls into a whirlpool by Nam Jae Yeop's irresistible proposal amid the greatest crisis of his life. Nam Jae Yeop, a hexagon full of a gold spoon background, warm visuals and excellent grades, but everything is a mask. As he begins to deviate from the life plan his father wants, his inferiority toward Kang Geon Tae also intensifies. As cracks start to form in his perfect daily life, he begins to run amok like a grenade with the pin pulled.
