"NCIS" may not work without Leroy Jethro Gibbs, but in the wake of his shooting, it will be Jimmy Palmer holding the team together as the 13th season gets underway.

"Jimmy Palmer is some of the glue that keeps the characters together - meaning he's the confidant, he's the friend," Brian Dietzen, who plays the autopsy gremlin, told TVLine.

The CBS drama will pick up right where last season ended with Gibbs (Mark Harmon) shooting in Iraq. As he's whisked away to undergo emergency surgery on a Navy hospital ship, DiNozzo (Michael Weatherly) and CIA Officer Joanna Teague (Mimi Rogers) will pursue the terrorist organization known as The Calling, which recruited the young boy who shot Gibbs.

Back at the Navy Yard in D.C., Palmer and his colleagues McGee (Sean Murray) and Bishop (Emily Wickersham) will assist the best they can in helping to track down The Calling as well as gather updates on Gibbs' condition to make sure he pulls through.

Of course, the Boss will survive but how he deals with the psychological and physical effects from being shot (and by a child, no less) will be the true test.

"It's more about how he comes back, how that impacts the team, and what the ramifications are," Weatherly told TVLine. "I think what we're going to have this year is a fundamental shift in the show - and that's a fascinating thing to see... I think the audience will respond with great interest to some of the tonal changes."

Dietzen added, "Getting shot by a child is pretty nasty, and pretty momentous. But this season our writers have pulled together one of their most cohesive plans in a long time."

Part of those plans include a fracturing relationship between Palmer and DiNozzo, whose relationship with Gibbs will also be tested.

"By the end of the year, his friendships versus his professional obligations are really going to be tested, specifically with DiNozzo. That friendship will be super-tested," Dietzen said.

"NCIS" will return on Tuesday, Sept. 22 at 8 p.m. on CBS.