NCIS investigates the shooting of Lt. John Maine in a national park, only to discover that he’s been listed as M.I.A., last seen in Afghanistan six years ago.
Maine survives the shooting but is unable to speak preventing any of our agents from questioning him. When his wife, Leah, shows up at the hospital, she’s confronted by Rachel Wells who claims that she’s married the same man - now known as Christian Wells.
Assuming a new identity, he married Rachel and claimed to have inherited a lot of money from his family. Rachel knew nothing of his past.
Maine flatlines and dies before Gibbs is able to question him. We eventually learn that while he was in Afghanistan he was part of a three-person deep undercover mission to track down a drug lord.
Maine, Lt. Holcomb and Sgt. Gontz concocted a plan to stea money from the drug lord, and while Maine stayed back and watched the money, the other two went in search for a vehicle. However, when they returned, Maine was gone and so was the money.
A few years later Holcomb hired a P.I., Peter Iger, to track down someone whom he thought looked like Maine.
The P.I. lies and tells Holcomb the man he saw wasn’t Maine, but after digging deeper and realizing what Maine was worth, Iger decided to confront Mayne in an attempt to blackmail him.
The plan backfired as Maine was also strapped, and a shoot out ensued - the opening scene of the episode.