The NCIS: Los Angeles cast is back at work, and the series spent the first day of production down by the LA River.

The CBS drama filmed the upcoming premiere, "Deep Trouble: Part 2," last spring, and the series will kick off season 6 production by filming "Inelegant Heart.' Directed by executive producer John Peter Kousakis, the episode is expected to air as the second of the new season.

While Callen (Chris O'Donnell), Sam (LL Cool J), Kensi (Daniela Ruah), and Deeks (Eric Christian Olsen) will all presumably make an appearance, Olsen worried his fans on Monday by posted a photo of his alleged new 'do.

Although the photo showed the actor with his long blond hair shorn short, viewers shouldn't worry since the shaggy-haired detective will keep his look from past seasons. The image was merely a Photoshop manipulation by an Instagram/Tumblr user that Olsen often retweets.

Details regarding the plot of "Inelegant Heart" are few and far between, but the team will spend the premiere trying to wrap up the season finale storyline. Callen and Sam will need to find their way out of the terrorist's submarine while Kensi and Deeks will spend the episode searching for them before time runs out.

Find out more when NCIS: LA returns on Sept. 29 at 10 p.m. ET.

Tags: NCIS: LA television CBS NCIS: Los Angeles