As Grey's Anatomy viewers learned on the season premiere, Seattle Grace is about to merge with Mercy West.

The result will be an influx of new characters, one of whom will be portrayed by Sarah Drew. The actress - most recently seen as Kitty Romano on Mad Men - will play the recurring role of a doctor named April.

The official hospital merger takes place on October 15.

Drew joins previously announced Mercy West newcomers Robert Baker, Jesse Williams and Nora Zehetner on the show. Their characters will compete with Seattle Grace regulars for jobs and patients.

The actress was originally cast on Inside the Box, a pilot created by Shonda Rhimes that was never picked up.

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