The first trailer forGrey's Anatomy's 12th season confirms that "everything has changed" since Meredith (Ellen Pompeo) returned to the hospital following McDreamy's (Patrick Dempsey) death.

So why is Amelia (Caterina Scorsone) knocking down a wall in Meredith's house? Why is that house such a mess to begin with? And why, God, why is Maggie (Kelly McCreary) punching some random blonde woman?

It looks like we'll have to wait until Grey's Anatomy returns Thursday, Sept. 24 (8/7c, ABC) to find out.