Senior Special Agent Jethro Gibbs' penchant for marrying redheads has long been a source of humor on 'NCIS,' and this season we'll finally get to meet one of his ex-wives, the oft-mentioned Diane.

According to TVGuide.com, 'Mad Men' alum -- and redhead -- Melinda McGraw will guest star as Diane on an episode called 'Devil's Triangle,' airing in early November.

She'll be joined by Joe Spano, who plays her character's other ex-husband (and Gibbs' best friend), FBI Special Agent Tobias Fornell.

"Imagine being the ex-wife of both Gibbs and FBI Agent Fornell," says 'NCIS' executive producer Gary Glasberg.

(S04E21) This week the NCIS team managed to put the viewer in the same position as Jenny. Unfortunately, that's not a good thing. When she opened up that cargo container and realized that she had been taken for a ride, I was right there with her, because the viewers had been on a ride of their own.

Now, I get how the formula works. NCIS is a mostly stand alone show, with serial elements. And I'm perfectly fine with that. I've been waiting anxiously for the last half of the season to get some answers about Tony/Jeanne and Le Grenouille, and that's fine. I enjoy the stand alone episodes while we wait. This week though, I would describe as a stand alone serial episode. What I mean is that while they were playing with the ongoing storylines, in the end it amounted to nothing. With the possible exception of knowing that Tony had dinner with Jeanne's mother, this episode could be left off the DVD and the story wouldn't miss a beat.