In 1950, just a few months after North Korean forces have overrun most of South Korea, an American-led UN coalition is deployed to Korea to aid the struggling South Koreans. General of the Army Douglas MacArthur devises a secret plan to attack behind enemy lines at the port city of Incheon.
The risky strategy is opposed by leaders of the other military branches, forcing MacArthur to devise a clandestine operation to gather essential information from within occupied Incheon by coordinating a weeklong South Korean intelligence operation known as "X-Ray". The linchpin of this top-secret incursion, Captain Jang Hak-Soo of the South Korean navy Intelligence Unit
and seven members of the X-Ray unit disguise themselves as a North Korean inspection unit and infiltrate the North Korean army command center in Incheon, coordinated by Soviet-trained Commander Lim Gye-Jin, a protégé of the North Korean leader Kim II-Sung.
Their prime objective is to determine the placement of North Korean defenses (such as mines and artillery) and the tactical characteristics of the Incheon harbor (notorious for swift currents and major tidal surges), and secure a lighthouse crucial to the landing's success.
Immediately suspicious of Jang's "inspection mission", Lim attempts to impede his comrade's investigation and orders his staff to monitor the new arrivals closely. The U.S. command relays MacArthur's orders to obtain navigation charts showing naval mine placements in the harbor and prepare a strategy to assist the coalition forces with landing an amphibious assault in a narrow two-hour window between tides. When contacts within the South Korean military intelligence unit known as KLO (Korean Liaison Office, predecessor to present-day South Korean Headquarters of Intelligence Detachment, or HID) warn Jang that time is running out to successfully complete the mission, he pushes his group to extremes. Meanwhile, in Tokyo, MacArthur prepares Operation Chromite, an invasion force of 75,000 UN troops and over 200 warships, to imminently depart for the Korean Peninsula.
