After being abducted by a child killer nicknamed "The Grabber," 13-year-old boy Finney (Mason Thames) is locked in a soundproof basement. On the wall, there is a black phone that does not work. Later, Finney hears the mysterious telephone ring and starts receiving strange calls from the killer's previous victims, who are now dead.

North Korean detective Chul-ryung (Hyun Bin) is sent to South Korea again on a new mission. His target is North Korean crime organization leader Jang Myung-joon (Jin Seon-kyu). In South Korea, Chul-ryung once again teams up with detective Kang Jin-tae (Yoo Hye-jin). Meanwhile, FBI agent Jack (Daniel Henney) joins Chul-ryung and Jin-tae in their pursuit of Myung-joon.

Chun-woo (Go Kyung-pyo), who is about to complete his military service, ends up with a lottery ticket worth 5.7 billion won ($4.1 million). But he soon loses the windfall as a breeze blows the ticket across the Military Demarcation Line. Yongho (Lee Yi-kyung), a North Korean soldier, finds the lottery ticket across the border.

In the 1980s, two elite agents at the Agency of National Security Planning, Park Pyung-ho (Lee Jung-jae) and Kim Jung-do (Jung Woo-sung), chase a North Korean spy who leaked top secret intel. The agents go head-to-head in an intense confrontation to prove their loyalty to their country and their respective units. Amid a growing obsession with hunting down the spy, the agents start to suspect and investigate each other.