Matt Smith

The Girl Who Waited is so last fall. This spring, get ready for The Impossible Girl.

"Sometimes the universe's greatest mystery is the person right next to you," a brand new Doctor Who trailer teases of The Doctor's latest companion.

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So who is Clara Oswin? According to The Doctor, "the only mystery worth solving."

Watch the trailer below.

Doctor Who premieres Saturday, March 30 at 8/7c on BBC America.