With a soviet-era nuclear weapon on the loose and two agents being tortured at the hands of a Russian arms dealer, the NCIS: Los Angeles team will have a bumpy start to season 6.

When viewers last saw the intrepid agents in "Descent," Deeks (Eric Chistian Olsen) and Sam Hanna (LL Cool J) were undergoing some unwanted dental surgery courtesy of Siderov (Timothy V. Murphy) while Kensi (Daniela Ruah) raced to save Michelle Hanna (Aunjanue Ellis) after finally receiving a kiss from her partner. In the meantime, Callen (Chris O'Donnell) helplessly waits back at the boat shed after realizing that Marcel Janvier (Christopher Lambert).

Following the agent's return in the season premiere, "Ascension," the team will have to deal with both the physical and personal fallout of previous events while also saving the city from a missing nuke.

"This premiere is unbelievable. It's one of the best we've had" Olsen recently told Access Hollywood as the cast began filming on the series 100th episode. "It's going to be everything you want it to be and more, and terrifyingly less as far as the outcome."

New promo shots for the episode focus on Callen, Kensi, and the Ops team. However, behind the scenes photos show a rather bloody Deeks while a new press release states that both he and Sam will spend sometime in the hospital.

NCIS: LA Season 6 to Uncover Deeks' Past  

However, Deeks will suffer greatly emotionally after the traumatic events and the LAPD Detective may even leave the team. His emotional state will color his interactions with Kensi following the latest development in the partners' relationship.

How Will The Deeks/Kensi Relationship Play Out?  

"[The premiere will have] the greatest and most honest scenes between Deeks and Kensi that we have ever had, which are heartbreaking," Olsen warns, according to Access Hollywood.

NCIS: LA will return to CBS on Sept. 24.