After teenage Han Li and Zhang Tie fail to join the Seven Mysteries Sect, a physician takes them in as apprentices. But their mentor hides a dark secret.
While Han Li saves Li Feiyu and learns that all of Mo’s previous disciples have vanished without a trace, Zhang Tie overhears Mo plotting with Yu Zitong.
Lee Do confronts a violent standoff and must decide how far to go to stop the killings, while suspicions about Moon Baek threaten their fragile alliance.
Guns reach bullied students and grieving parents, sparking new tragedies. Lee Do uncovers a network delivering weapons to vulnerable people across Korea.