As "NCIS: Los Angeles" fans gear up for the explosive, two-hour premiere of the hit CBS show tonight, ET's Kevin Frazier gets the details about the new season straight from LL Cool J and Chris O'Donnell, as the two get up-close-and-personal with their fans.

"Season two is going to pick up exactly where we left off at the end of season one," Chris tells ET. "My character's looking at a grave stone of his sister that he never knew he had, and realizes that someone's been watching him."

Chris also dishes to ET that Eric Christian Olsen is new to the cast and that a new actress will join the cast this season, but he's staying mum on who that mystery woman is.

Kevin welcomed the stars to San Diego's annual fleet week, honoring the American military. And the men who play Naval investigators on TV enjoyed meeting the real deal and engaging in a question-and-answer session moderated by Kevin.

Watch the season premiere of "NCIS: Los Angeles" tonight at 9 p.m. on CBS. Also, watch the video above to see Chris and LL ask our ET Facebook fans a question. Click here to join the conversation and give us your answer!