Sasha Alexander and Sharon Lawrence Sasha Alexander and Sharon Lawrence

Tuesday's episode of Rizzoli & Isles will feature a case of mistaken identity, but for Maura, it's a case of learning her identity.

For the first time in her life, Maura (Sasha Alexander) will come face-to-face with her birth mother Dr. Hope Martin (guest star Sharon Lawrence), but this is no simple meet-up for coffee. How can it be when Hope doesn't even know that her daughter is alive? Lest we forget, Maura's crime boss father Paddy (John Doman), who feared that his father/mob honcho would kill Maura, asked Constance (Jacqueline Bisset) to adopt his baby girl and told everyone — including Hope — that Maura had died during birth.

So how do Maura and Hope finally reconnect? Does their reunion go swimmingly? We caught up with Lawrence to see what's in store.

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Were you a fan of the show before you joined?
Sharon Lawrence:
I was really interested in the commitment of TNT to create a show with women leads that's run by women. ... I was keeping my eye on it and really spent more time toward the end of the first season catching up. What really made me want to be a part of this was the compelling story that Maura Isles has been living — this challenge of feeling the absence of a very basic part of self-knowledge. I saw the episode where she learned who her father is. The painful acknowledgement of your DNA being something that you never imagined and still having missing pieces is so poignant. And Maura is someone who is analytical and intellectual, who really thrives on facts, on knowledge.

Do you get her hesitation in looking up Hope?
Yes, but it's tough. I don't think it's something you can jump into right away. For me, it makes a lot of sense that she could never rest with just a name, whether it's a need to put a visual to who your parents are or if it's to really understand why that feeling of abandonment can't go away. Sometimes we make up stories for ourselves, and she just can't fill in the blanks with imagination. Maura needs knowledge. She's driven to understand who she is, not just by nurture, but by nature. She finds out some compelling truths about herself.

And you guys come together through a case. How else would it happen, right?
Exactly! [Laughs] They are brought together in the form of colleagues. Maura reaches out to Dr. Hope Martin, who is in the same field. I think it's understandable that these two women share the same passion for science. The fact that they are able to meet in a lab makes great sense. Dr. Hope Martin is someone who created a particular technique to identify bodies. She operated in the Dark Ages of the '80s and '90s before DNA sampling was perfected, so she did see value in the importance of identifying remains so that families and individuals could be reunited with each other. Given that she has such a huge missing piece of her story, that drives her to fill in the missing pieces for other people. These are painful things she's avoiding.

What is their interaction like? Obviously Maura knows from the start they're related, but Hope doesn't.
For Maura, this reunion is such a kaleidoscope of emotions. She's working on solving a case and is trying to concentrate, but she can't help but observe and take in Hope and notice their similarities. And they have a lot of similarities! I think what's fun to see is the behavior between these two women, the physical characteristics and their actions. We had fun, me coming in and studying Maura's quirks and finding ways to include them.

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Does Hope suspect anything or figure it out?
Hope kind of senses something just based on Maura's actions, but she doesn't really know what's going on. Their bond is so deep, so strong and so shrouded. It was really so impressive to see Sasha Alexander embody this, capture this and reflect it back. She's such a great actress.

Do we learn more about Hope's relationship with Paddy?
I'm in three episodes and there's a progression as to how this whole arc unspools. ... It gets very interesting.

When does Hope learn the truth?
It's drawn out. So don't look for it soon! Jane and her mother (Lorraine Bracco) are very much a dynamic in this reunion if you can call it that. Hope has daughter from her marriage who has absolutely no idea about any part of this. ... There's a lot to play. Maura's too smart to throw in a bit of information that could blow up in everybody's face, so it'll take a bit. This is a show about discovering the missing pieces and connectors and nothing's simple.

Will you return beyond these three episodes?
I haven't heard yet, but it would be a pleasure! It depends on how they unfold the story the rest of the season. I would love to though.

Rizzoli & Isles airs Tuesdays at 9/8c on TNT.