The Iraq Conspiracy ("Kumar Gate"): Je-ha's lover, Raniya, was not killed randomly. She worked as an interpreter during high-level oil and arms negotiations in Iraq and overheard corrupt Korean politicians—led by candidate Park Kwan-soo—facilitating illegal transactions. Kwan-soo ordered her execution and framed Je-ha to cover up the scandal.
The Truth About An-na's Mother: Uhm Hye-rin (An-na's biological mother) did not die by suicide. Choi Yoo-jin arrived at the scene while Hye-rin was dying of a drug overdose. Rather than administering the life-saving medication nearby or calling emergency services, Yoo-jin stood by and deliberately allowed her to die to ensure Jang Se-joon remained bound to her politically.
Choi Sung-won's Betrayal & Finale Detonation: Choi Yoo-jin's half-brother, Choi Sung-won, allies with Park Kwan-soo and infiltrates JSS with a dirty bomb to seize control of Cloud Nine. In Episode 16, realizing the bomb cannot be disarmed, Sung-won shoots Choi Yoo-jin and flees (later executed by Secretary Kim). Facing imminent death inside Cloud Nine, Yoo-jin makes peace with her husband. Jang Se-joon chooses to stay in the blast zone with her as the subterranean bunker explodes.
Resolution: Je-ha succeeds in rescuing An-na before the blast. He leaks the "Kumar Gate" evidence to the public, destroying Park Kwan-soo's political career, which leads Kwan-soo to hang himself in his getaway vehicle. Je-ha is cleared of all false charges, and he and An-na relocate to Spain to live a peaceful life together.