By Sandra Gonzalez
Updated November 28, 2011 at 11:14 PM EST
Credit: Doug Hyun/TNT

Rizzoli & Isles begins its final stretch of season 2 episodes tonight on TNT with more of the same — and that’s anything but a bad thing.

In its time on the cable network, the show has found a comfortable existence on Procedural Way, its two excellent female leads, Sasha Alexander and Angie Harmon, at the helm. And in these last five episodes of the season, Alexander, who navigated the waters over at NCIS for two years before her Rizzoli gig, says the show’s seemingly simple formula has more than a few turns in store for viewers.

“The [cases] get really strong,” she says. “In these episodes, Jane and Maura’s friendship gets tested in some really unexpected ways because of the mysteries and the way the mysteries unfold. The boundaries of being friends but having work-related rules they have to abide by, it’s just going to be interesting to see how [they] respond to it all. They both have huge disagreements and it puts them both on either side of the fence.”

One issue the women will have to grapple with? What happens when Jane’s screw-up brother Tommy (Colin Egglesfield) and Maura have a little chemistry? “How does it affect their friendship? Where does it go?” teases Alexander. “I find it really funny — funny stuff happens. But then it turns dramatic because he might have gotten himself in trouble.” In addition, Tommy now also knows that Maura’s real father is Irish hitman Paddy Doyle. “That kind of makes things a little tricky because now he is part of the inner fold of knowing this very very sort of dangerous information,” says Alexander.

For Alexander, the pleasure of playing Maura Isles is the fact that stories that have been woven to make her — and her relationship with tough-talking Jane Rizzoli — so much more than what they could be. “These women are very different, have different colors, we learn more about them as the series goes and when they fight, they’re not being catty,” she says. “They aren’t fighting over who looks better in a little black dress. They’re fighting over real life issues. And these real life issues involve a personal relationship and it also involves work.”

The trials that await the women in the last five episodes — and, in particular, the season finale — will “leave [fans] wanting to know what happens between these women,” says Alexander. “I think the finale really tests their friendship and their relationship…it’s very powerful.”

(Erin Strecker contributed to this report.)