My Secret, Terrius

My Secret, Terrius (2018), directed by Park Sang-hoon and Park Sang-woo and written by Oh Ji-young, is a 32-episode South Korean mystery-comedy television series broadcast on MBC. The narrative follows Kim Bon, a legendary National Intelligence Service (NIS) black-ops operative code-named "Terrius". Three years prior to the main storyline, a botched covert mission in Poland resulted in the tragic death of the woman he loved and framed him as an internal mole, forcing him into a solitary, paranoid existence in a quiet Seoul apartment complex.

His neighbor, Go Ae-rin, is an energetic single mother navigating sudden grief and financial hardship following the abrupt and mysterious death of her husband. When Bon realizes that Ae-rin’s family is unwittingly entangled in the same lethal conspiracy that destroyed his past, he takes on the unexpected cover of babysitter for her mischievous young twins.

As Bon steps into the chaotic realities of domestic childcare and elementary school social circles, he partners covertly with both official intelligence agents and the "Kingcastle Information System" (KIS)—a hyper-efficient grassroots neighborhood watch of local parents. Together, this unconventional alliance works to peel back layers of corporate espionage, international assassination, and institutional betrayal, delivering a balanced blend of spy thriller suspense and family-oriented comedy.

At its core, My Secret, Terrius demystifies the romanticized myth of the solitary hero, illustrating that the greatest defense against darkness is not solitary strength or state surveillance, but everyday human connection and community solidarity. Through Kim Bon’s transition from a traumatized black-ops weapon to a nurturing caregiver, the creators emphasize that healing trauma requires re-engaging with life rather than isolating from it. Furthermore, by placing middle-class apartment parents and a grieving homemaker on equal operational footing with elite spies, the series celebrates the unsung competence, resilience, and emotional intelligence of ordinary people in everyday society.

Critical readings of the series include:

Broadcast in late 2018, My Secret, Terrius revitalized the Korean drama hybrid format of the "Domestic Action-Comedy" (in the lineage of shows like My Fellow Citizens! and The Fiery Priest). It tapped into cultural conversations regarding the burdens of modern parenting, high-rise apartment isolation, and the power of neighborhood parenting collectives such as "Mom Cafes" and KakaoTalk groups. The drama demonstrated that high ratings did not require graphic violence or grim melodrama, proving that high-stakes espionage blended with slice-of-life domestic warmth appealed broadly to domestic and international audiences.

The series received widespread acclaim for So Ji-sub’s charismatic performance balancing deadpan comedy, action, and gentle chemistry with child actors, as well as the comedic brilliance of the KIS trio (Kim Yeo-jin, Kang Ki-young, and Jung Si-a). Viewers praised the well-balanced narrative pacing that harmonized suspenseful set pieces with cozy family dynamics.

Minor criticisms noted that the Cornerstone international conspiracy relied on predictable spy tropes and simplified tactical scenarios, while a segment of viewers seeking conventional melodrama romance expressed slight disappointment over the restrained, platonic-leaning ending. Overall, it was regarded as a quintessential, highly re-watchable K-drama.