This joint Korean-Chinese-Japanese drama follows six elite police experts covertly assembled to protect their nations' financial future. Set in the near future, "Strangers 6" takes place around "Haiwan", a fictional Chinese megacity and economic hub where businesses from all three countries operate without borders. However, the metropolis faces total annihilation from a massive earthquake predicted to strike within three months. The only salvation is installing a cutting-edge device beneath the city, requiring advanced technology and a colossal trilateral investment. Recognizing this as vital to their economic survival, the nations quickly launch this high-stakes joint operation. But time is running out, while somebody is actively trying to sabotage the project by assassinating anyone involved.