What Has Angie Harmon Banned Sasha Alexander From Wearing on the 'Rizzoli & Isles' Set?

Plus, the on and off-screen friends preview what's next for Jane and Maura in Season 4.

Sasha Alexander and Angie Harmon on the "Rizzoli & Isles" episode "In Over your Head"

When Angie Harmon and Sasha Alexander entered the interview cubicle at a recent press day for Season 4 of their top-rated crime series "Rizzoli & Isles," the duo was finalizing their plans to attend the network's murder mystery bash together later that evening. When Alexander complained that her energy level was bottoming out and Harmon offered to share her coffee, the former "NCIS" star, who worries about getting diabetes like her father did, knew to decline the swig of Starbucks because Harmon adds too much sugar. They finish each other's sentences, laugh at each other's jokes, and give each other fashion advice.

[Related: Summer TV Tune-In Guide]

Take the time, for instance, that Harmon forbade her co-star to wear Birkenstocks on set. "We were in rehearsal and I look down in literally the middle of the scene and I'm like, 'Listen, Maura, you, um, what are those?' I completely came out of character when I saw her shoes. She's like, 'They're Birkenstocks.' I'm like, 'No, those have to go. You can't wear those ever again. I can't even rehearse with you right now,'" Harmon recalls, giving her best stink-eye anytime Birkenstocks are mentioned. "But Celine just came out with these 'Birkenstocks' lined with fur. I went in, bought a pair — not cheap — just to play a joke on her because my favorite thing is to make her laugh. I walked into the set and said, 'Well, hello.' [She lifted her leg and demonstrated how she showed off the sandals.] If you're going to wear Birkenstocks, they need to look like these."

Alexander responded to the recollection with a slight eye roll before a mini-squeal of delight. "It is the couture Birkenstock. But now she's going to give them to me."

[Video: 'The Bridge': FX's Next Great Drama?]

It would appear that Harmon and Alexander have taken their work home with them. Just as the friendship between medical examiner Maura Isles and no-nonsense Boston cop Jane Rizzoli has grown fiercely over three seasons, so has the real-life bestie bond of the actresses who play them. "One thing that I've always liked about our show and feel helped in the beginning was that the audience has been growing with the girls and gotten to know them as they've gotten to know each other. When we started the show, they weren't besties who grew up together. They're individuals doing their jobs really well," Alexander explained. "We didn't force the audience. Don't you love them? Aren't they cute because they dress the same way? [Instead the audience] has been part of that process. They've gone through a lot; they're at a different place, and they're exploring that more in Season 4. It's fun to have the scenes together, but you could do a whole episode that is all Jane."

Harmon was quick to add, "Or the reverse."

[Related: 'Major Crimes': Cast Promises 'There's Always a Dead Body']

Season 4 picks up with Rizzoli trying to lift Isles out of the deep funk that donating a kidney to save a half-sister she barely knows without so much as a thank-you from her family caused. Alexander said, "Stuff dealing with Maura's family is affecting Jane and the other detectives. It is personal and very intertwined and makes Maura realize that Jane is her family, and she's not sure who these people are to her."

These people include her mob-boss father, Paddy Doyle (John Doman), whose pending murder trial will play out onscreen. "It's complicated. As much as we want to put him away, we care about her and he's her dad," Harmon said. Alexander followed, "It's hard because there is a connection, but he's such a bad guy."

Isles isn't the only one dealing with personal issues. In the first episode, Rizzoli's broken soldier beau returns after a successful surgery for one passionate night before he announces that he is headed back to train in the same therapy that helped him overcome his bedroom-bungling PTSD.

[Photos: Model Citizens of Primetime TV]

"It's so convenient. Just when his penis starts working, they ship him off again," Harmon said. "It's like the only person they want to get any action is my mom."

Of course, having no love prospects leaves the ladies free to close cases, and this season promises some doozies like assassinations of state senators, a serial killer, and the brutal killing of an earnest journalism student. Harmon said, "A lot of the cases seem to have more weight to them. There are a lot of heavier, more serious, and more emotional crimes."

The intensity challenges the women professionally, which they appreciate; however, Harmon's dream episode is far lighter in tone. She fantasizes about the day when Rizzoli gets a makeover to match her real-life counterpart's fashion-plate status. "This is what I wear at 5 in the morning," Harmon says, pointing to her sky-high fashion-forward heels and short shorts. "Have you seen what they make me wear on the show? I'm jealous of Sasha daily, hourly, all the time."

[Related: 8 Questions With Jon Tenney of TNT's New PI Series 'King & Maxwell']

This is when Alexander stepped in like only a true friend can. "She comes in to work every day with a far better wardrobe than Maura's. Her real-life clothes are that. One thing about Angie that I love is that she wears Cherry Chapstick on the show every day and she still looks good. Plain Jane my butt!"

She also reminded her partner in crime show that being the natty onscreen dresser has its drawbacks. "I can't run very fast [to the scenes]. And this one's running like a gazelle. I'm like, 'Could you slow down?' I can't stay in the shot with her because she's a speed demon."

Harmon considered the trade-off, and it was easy to see from the giant smile that spread across her face that a visual had suddenly popped into her head. "The best part is when we all take off to go to the crime and this one's in her pencil skirt and Louboutins going [does her best whiney voice], 'Jane, wait.' We all look and here comes Maura. Tink, tink, tink," Harmon teased, adding hand gestures that would suggest delicate footsteps in heels, before reconsidering. "But could you please at least do [Jane's] hair?"

[Related: 9 Things to Know About 'Falling Skies' Season 3]

Alexander defended Plain Jane once again. "You know what I love is that Jane doesn't want a makeover. She isn't jealous of Maura or want to be dressed like Maura. She doesn't care."

The epiphany led the pair back to an earlier joke about the show's potential to stand the test of time or at least inspire a Funny or Die skit. "We joke that we're going to do this show so long that it's going to be that whole Angela Lansbury thing," said Alexander, mentioning that scenes like the one where they are jogging in the park as part of Isles's recovery would certainly look different.

Harmon played along with the bit in her best old lady voice. "We'd have those rolling walkers and we're just really old pushing them. 'Maura, what do you think about the killer? I'm gonna put my teeth in. We gotta solve the case.'"

Alexander continued, "'Hold on, I need my lashes and wig.'"

"Rizzoli & Isles" premieres June 25 at 9 PM on TNT.