Hae-sung is caught off guard when he recognises Soo-ah's childhood name, Bong-ja, which stirs memories of his first love and distracts him from his focus. Despite the emotional turmoil, Hae-sung pushes forward with the mission to uncover the secrets behind the third ghost story. However, a missing key component forces Soo-ah to join the mission despite Hae-sung's strong opposition to her involvement.

After uncovering the possibility of a mole within the NIS, Hae-sung becomes increasingly distrustful of those around him, causing him to question the mission's integrity. Meanwhile, Soo-ah exposes a secretive scheme within the school that guarantees top grades for VIP students. As the web of secrets deepens, Hae-sung uncovers the connection between the gold bars and Chairwoman Seo, prompting him to vow to end her sinister plans.

As Soo-ah recovers in the hospital following the attack during the break-in, Hae-sung and the team uncover the culprit: Lee Jun-ho, the mathematics teacher. When Hae-sung detects his father's notebook missing, he realizes that Seo Myung-joo orchestrated the break-in. After Lee Jun-ho's arrest and confession, the revelation of the school's grade-rigging scandal throws the institution into chaos. Amid the turmoil, Hae-sung stumbles upon a crucial clue to the final scary story.