Tatiana Maslany Tapped to Star in BBC America’s ‘Orphan Black’ Sci-Fi Series

"The Vow" actress Tatiana Maslany will play a suicide witness who discovers she's a clone of the woman who killed herself

"The Vow" actress Tatiana Maslany has been tapped for the lead of BBC America's upcoming original sci-fi series "Orphan Black," the network said Monday.

Maslany will play Sarah, an outsider, orphan and street-wise chameleon who has a murky past and tenuous future after she witnesses a woman’s suicide. After deciding to assume the identity of the dead stranger who looks just like her, Sarah learns that she and the dead woman are clones.

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As Sarah searches for answers, she also discovers there are more clones out there, who were planted in unsuspecting birth parents and nurtured in completely different circumstances and have been targeted by an assassin who's been killing them off, one by one.

The 10-episode series, which is being produced by Temple Street Productions for BBC America and Canadian cable channel Space, begins production in Toronto in October. Additional casting will be announced soon.

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In addition to her role in the Rachel McAdams-Channing Tatum film "The Vow," the Canadian-born Maslany starred in the 2011 thriller "The Entitled" with Ray Liotta and Victor Garber.

"Orphan Black" is co-created and executive-produced by Graeme Manson ("Flashpoint") and John Fawcett ("The Secret Circle"); Manson will also write the project, with Fawcett directing. Ivan Schneeberg and David Fortier ("Being Erica") will serve as executive producers for Temple Street.