In 1996, two Navy personnel were killed in a Virginia Beach apartment. The victims – Elise Makdessi and Quincy Brown – were coworkers at Oceana Naval Air Station. Makdessi’s husband, Eddie, said the couple had returned home from dinner and were accosted by Brown. Eddie Makdessi said Brown sexually assaulted and stabbed Elise. Eddie told police he was able to grab a gun and shoot Brown, but it was too late to save his wife. Because two sailors had been murdered, NCIS was called to the crime scene that very night. With not one, but two of their own now dead, the agents would not rest until the mystery at the heart of this case was solved. It would take 10 years as NCIS followed this twisting, turning tale that spanned two continents before coming to its stunning conclusion.

The agent who inspired CBS' "NCIS: New Orleans" takes viewers inside his real-life cross-country search for the murderer of a woman in San Diego.

In June 2001, the bodies of Navy Petty Officer Lea Anne Brown and her friend Michael Patten, a bank employee, were found in the woods off a rural road in Accokeek, Maryland. Both had been shot twice in the head. They appeared to be targeted murders -- but why? Neither had any connections to any criminal activity, and there wasn't anything else that would make them obvious targets of such a vicious crime.

A Navy contractor who wanted to sell secrets, two hackers who stole 220,000 U.S. military personal records and 17 sailors killed in a terrorist attack aboard the USS Cole. NCIS agents open up about their emotions, fears, frustrations and successes in solving investigations that have national and international impact - the cases they can't forget.

In 1989, Annie Tahan disappeared without a trace. She left behind a newborn daughter and her boyfriend, Chief Petty Officer Michael Paalan, who told police that she had walked out on him. Four years after she disappeared, and with little to go on, authorities in Charleston, S.C. asked NCIS for help. "The mere fact that Michael Paalan was an active duty sailor at the time, we had an obligation to seek out the truth," said retired NCIS Special Agent Pete Hughes. Did Paalan have something to do with Tahan's disappearance? It would take years of challenging investigative work, multi-agency cooperation, surveillance and a sting operation to get answers. Moreover, they were investigating one of their own, making the case even tougher.

When the investigation of a murdered Navy petty officer goes unsolved for nearly two decades, an NCIS agent goes undercover to turn up the heat on a suspect