Mamie Gummer Mamie Gummer

Sure, Mamie Gummer is the look-alike daughter of screen legend Meryl Streep, but the 27-year-old is also one of the stars of ABC's new medical drama Off the Map, premiering tonight at 10/9c. Here are four things you should know about the series' resident infectious-disease specialist.

1. Her proudest credit is 2007's Evening.
The film costarred Gummer's mom, Glenn Close, Vanessa Redgrave, Toni Collette, Claire Danes and the late Natasha Richardson. "It was such an incredible constellation of women," she says.

2. She's a scuba diver.
And she plans to make the most of OTM's Hawaiian location. "I haven't been diving here yet, but there are a couple of shipwrecks to explore."

3. She attended Northwestern University with OTM costar Zach Gilford.
He recalls performing in the play The Laramie Project with Mama Meryl in the audience. "Having her there was a pretty big deal," recalls Gilford. "We all wanted to make her cry."

4. She's planning a wedding to theater actor Benjamin Walker.
How do they make it work when she's in Hawaii and he's on Broadway (he just finished starring in Bloody, Bloody Andrew Jackson)? "You just do," Gummer says. "The new iPhone 4 with FaceTime [video chat] is amazing."

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