The team is called to investigate when a Marine sergeant falls from the roof of the building where she shares an apartment with her sister. Gibbs encounters Dr. Grace Confalone at the hospital and learns that Grace was treating Sgt. Hill, but Grace will only give vague hints that Sgt. Hill's fall was possibly a murder attempt.
Sgt. Hill's commanding officer had been concerned about her since her return from Afghanistan and had ordered her to see a psychiatrist. The team learns that a civilian contractor, Griffin Dorn, had offered her a lucrative job after her hitch with the Marines was up.
The sergeant succumbs to her injuries, and Dr. Confalone reveals that Sgt. Hill was involved in a murder cover-up, but didn't know if the murder in question took place overseas or in the States. Torres has a hunch that it may have something to do with the death of an elderly man in the apartment building.
When the team learns that Sgt. Hill's sister found the body of the elderly man, the pieces start to fall into place. They discover that the neighbor had a valuable coin and gold collection, and the sergeant's sister and her boyfriend, the building maintenance guy, had been plundering it.
When the neighbor caught the maintenance guy, the maintenance guy killed him, and Sgt. Hill's sister helped make it look like an accident. However, the boyfriend was concerned that Sgt. Hill would convince her sister to go to the police, so contrived to kill her, too.
This episode was dedicated in memory of NCIS showrunner Gary Glasberg.