Supergirl: The New 52 Book One

Lost on a strange world, Kara Zor-El begins her journey to becoming Supergirl.

After crash-landing on Earth, Kara Zor-El of Krypton awakens with no knowledge of where she is or how she came to be there. Surrounded by hostile strangers speaking in an alien language, Kara is utterly lost and cut off from everyone she's ever known.

Or is she?

Collects Supergirl #0-13, Superman #0 and #6, and Superboy #0 and #6.