[8][9] A group of spies called the 5446 Corps were trained by North Korean elite special forces since their youth, ostensibly towards the lofty goal of unifying Korea.

Passing boring time without receiving any orders from the North, they gradually get used to life as ordinary neighbors in a small town until one day, their mundane lives are turned upside down when a "secret and great" mission is suddenly assigned to them.

To prevent the elites from falling into enemy hands, the North Korean government orders dozens of active duty spies to take their own lives.

[32] 72 hours after its release, the number of tickets sold for Secretly, Greatly crossed the 2 million border, making it the fastest film to do so.

[38] On its eighth day of release, the film became the fastest movie to reach the 4 million mark in audience number, tied with The Host, Transformers: Dark of the Moon, The Thieves, and Iron Man 3.

It then expanded across the region during the season with runs in Japan, Indonesia and Hong Kong, where Kim made his appearance for the local premiere in late July.