NCIS: Los Angeles premieres Tuesday, September 21, after NCIS.

In the two-hour, second-season opener, the focal point is Lt. Marty Deeks (new cast member Eric Christian Olsen), who was working an undercover job for the LAPD.

After both his targets turn up dead, the team begins to worry when Deeks goes off the grid. Hetty pledges the agency's full support to hunt down the missing officer:

[video url="http://www.tvfanatic.com/videos/ncis-los-angeles-season-premiere-sneak-peek/" title="NCIS: Los Angeles Season Premiere Sneak Peek"] [/video]

In addition to Callen and Sam, explosive premiere is expected to indoctrinate Olsen into the fold, as well as featuring an increased dose of Kensi. No complaints here.

To get caught up on the entire series to date, follow the jump for a six-minute compilation of clips CBS put together summarizing NCIS: Los Angeles' first season ...

[video url="http://www.tvfanatic.com/videos/ncis-los-angeles-season-1-recap/" title="NCIS: Los Angeles Season 1 Recap"] [/video]

Steve Marsi is the Managing Editor of TV Fanatic. Follow him on Google+ or email him here.