How To Get Away With Murder on ABC hasn't even aired yet, but the Shonda Rhimes show is already booking more stars.

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How To Get Away With Murder stars Oscar nominee Viola Davis who plays a law professor at a prestigious Philadelphia University, who along with her students becomes involved in a murder plot.

On Saturday it was revealed that British actor Elliot Knight had booked a guest role on the crime drama. TVWise reported that Knight's role is being kept under wraps, but the actor will appear in the third episode this season. Knight is best known for British TV, but appeared in the Dangerous Liaisons pilot that wasn't picked up by ABC.

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Earlier this month The Hollywood Reporter also reported that Alysia Reiner, known recently for Orange is the New Black, had also booked a role on the show. Reiner is set to play a prosecutor who goes head-to-head with Annalise (Davis' character). She was on Orange as Natalie Figueroa, the executive assistant to the warden at the prison.

How To Get Away With Murder show runner Pete Norwalk said about Davis' character "She's the center of mystery for our audience to wonder about." He also noted that her motives will remain a mystery.

"Whether she's morally questionable or not, it comes to the heart of the character and what she's been through," he said. "The real adventure is the peeling back of the onion and what drives her to this place and what drives her to justice. Justice is very complicated and much more corrupt than you'd think."

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