The Only Easy Day (S01E02)

When three SEALs interrupt a drug deal, stealing the drug money -- two people end up dead, including an undercover LAPD officer. When NCIS watches the surveillance footage, Sam recognizes a former SEAL colleague, despite his mask, and the hunt is on to find the other team members and the evidence needed to convict them. Sam confronts his old friend, but gets little satisfaction. He's personally offended that his former brethren could violate their code so profoundly, particularly when one of their team turns up dead, having been killed in the initial robbery. In a surprise twist, the investigation leads NCIS to discover the undercover cop wasn't there to take down the drug dealers, but another LAPD officer who is leading a double life selling drugs. Using their skills as interrogators as well as their undercover acumen, Sam, Callen and the team are able to arrest the SEALs involved, as well as take down the dirty cop. (CBS TV Network)