Mu-jin and his team look for evidence to reclassify Nurse Cho Eun-young's suicide as an industrial accident, aiming to hold the hospital accountable for covering up suspected workplace bullying and medical malpractice. However, with Mu-jin blacklisted from the hospital, it falls to Gyeon-woo to infiltrate the facility and locate the one piece of evidence Mu-jin remembers seeing while possessed.

Mu-jin's father suspects his mother of having an affair and asks him to investigate. When Mu-jin visits, he encounters a ghost, a close friend of his mother, seeking justice. Following his mother to her university, Mu-jin uncovers a mysterious test that may explain the ghost's tragic death.

With the protest shut down by police, Mu-jin and the workers regroup to form a union, vowing to fight to the end. However, when the university refuses to meet their demands, they have no choice but to go on strike. Just as the situation begins to look hopeful, they encounter unexpected backlash from students, prompting them to question the very cause for which they have been fighting.