Graham Patrick Martin, Mary McDonnell

Major Crimes' third season will be a family affair.

Not only does the case in the premiere (Monday, 9/8c, TNT) involve two children who have gone missing with their father while everyone in Major Crimes points the finger at the mother, but it also sets up a season that explores what "family" truly means.

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"The theme of our first 10 episodes this season is expectations," creator James Duff tells TVGuide.com. "We have an expectation of a lot of things in our lives that it turns out that we have no right to expect. Family is not a given. Family is something you are sometimes obligated to create for yourself and that you embark upon with other people."

Indeed, over the first two seasons, Capt. Sharon Raydor (Mary McDonnell) has built a new family dynamic with Rusty (Graham Patrick Martin), an orphan whom she originally took into her home while he prepared to testify as a witness in a murder case. But just when it seems like Sharon might be ready to make their arrangement more permanent, Rusty gets a surprise: His mother (Ever Carradine) returns to his life.

"We begin our first episode with a different Rusty," Duff says. "He has changed quite a bit. The experience of testifying on his own and having his say in the courtroom, reduced the whining, reduced the teenage angst. He's sort of moving beyond and looking into his own heart and how he can make things better. Then, out of the blue, he's knocked off stride by the reappearance of [his mother] who he had thought he was separated from for good."

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And Rusty has no plans of sharing the surprise with Sharon — at least not right away. "You get close to someone, but that doesn't mean that on certain intimate issues you are inflexibly honest," Duff says. "Sometimes we like to sort out our own feelings about circumstances before we involve the people who are closest to us, and that doesn't mean there's a loss of love or a loss of respect. It means there's fear and anxiety. The anxiety he has about his mother will reveal itself, and he [does] introduce his mother to Sharon," Duff says. "His mother has a very different take on where he is in life than Sharon does."

But Rusty's dilemma is only half of the story. His mother's return comes just as Sharon begins to consider making her arrangement more permanent by legally adopting him. That will raise the eyebrows of Sharon's "real" family, including her husband Jack (Tom Berenger) and her yet-to-be-cast son Ricky. "As she moves forward to adopt Rusty  — or as the questions appear: 'Should I? Do I want to be [his mother]?' — her already established family weighs in in different ways," Duff says. "How do you include other people? What does the word family mean? Do you have any right to expect that your family will always be exactly what it is?"

Of course, the Major Crimes work family dynamic will also be explored. "There will be more personal life stuff," Duff says. "Sykes [Kearran Giovanni ] gets flowers [in the premiere]. Who did they come from? Is she dating somebody? Flynn [Tony Denison] keeps talking about his daughter. His daughter is going to show up, and he keeps pretending to his family that he and Sharon are closer than they are. How long is he going to get away with that?"

Elsewhere, Sanchez (Raymond Cruz) will take in his mother while wrestling with an old case when someone he arrested for manslaughter might actually be innocent. And Tao (Michal Paul Chan) will serve as a police consultant  for a TV show's writers' room. (He's part of a Hollywood family that they don't even know about!" Duff says.) And Provenza (G.W. Bailey) will be roped into keeping Rusty's secret about his mother from Sharon.

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But the return of Rusty's mother also forces Rusty to look at his other secrets, including his sexuality. "It sets up identity issues and the expectation that someday you will know who you are, which is the most fundamental piece of misinformation we probably are ever sent off from home with," Duff says. "It's so hard to know who you really are. He's going to be testing who is, and he's going to come out eventually."

And how will Rusty's "family" at the precinct receive the news? "In 1973 I came out to my friends," Duff says. "The process of living your life as a gay person has changed enormously, but the process of coming out hasn't changed very much at all. It's more a problem for Rusty than it is for other people. It's saying, 'I'm really different from you,' and when you say it out loud, it just makes it more true. I think it's very hard for him, but the reaction from the squad is different than what he expected."

And that ultimately reinforces Duff's theme for this season. "Expectations can ruin us, but without expectations we sometimes don't perform," Duff says. "It's about how to harness the power of expectation to do good. Expectation is a tricky thing, but it's part of what made humans king of the jungle. Our ability to anticipate and look into the future and to understand the possibilities that await us, that's what moves the human race. And yet it's also a bit of a struggle."

Major Crimes premieres Monday at 9/8c on TNT. For more on the premiere, watch the video below to see why the show is our editors' pick: