Prepare yourself for a wild ride!

NCIS: Los Angeles Season 5 Episode 17 begins with the brutal execution of an undercover ATF agent and never lets up. NCIS gets a tough case that's a little out of their normal arena and that creates challenges for them.

They have to find out how the undercover agent's identity was revealed in order to prevent additional deaths. They track the evidence and Sam infiltrates the criminal organization. It's a risky move with a shocking outcome.

In Afghanistan, it's not any easier for Kensi. She goes missing from the base and for a jaw-dropping reason.

Watch NCIS: Los Angeles online to find out what happens before you get spoiled!