Credit: Sara Ramirez on Twitter Photo: Sara Ramirez and Caterina Scorsone

Whoever is operating the hospital P.A. system on Grey's Anatomy might have to get a little more specific when paging "Dr. Shepherd."

That's because Private Practice star Caterina Scorsone is heading to the mothership to reprise her role as Derek Shepherd's sister, Amelia.

The news of Caterina's return first broke in March, but now we know that she'll pop up on the April 24 installment of the show — thanks to ABC's synopsis for Season 10, Episode 21: "Change of Heart."

Here's how the network summarizes this episode:

Jackson [Jesse Williams] is given the daunting task of delivering disappointing news to the doctors. Meanwhile, Derek's [Patrick Dempsey] sister Amelia [Caterina Scorsone] drops by for a surprise visit, Richard [James Pickens Jr.] surprises Catherine [Debbie Allen] in Boston, and when Bailey [Chandra Wilson] gets frustrated by the slow pace of her research, she makes a risky decision.

So many teases, so little actual information! This synopsis leaves us with more questions than answers. For instance, what's the bad news Jackson has to bear? What risky decision is Bailey making? And as cool as it is that Richard is traveling cross-country, why's he going?

What do you think might be the answers to these questions? Speculate away below!

Grey's Anatomy airs Thursdays at 9 p.m. ET on ABC.

Dan Clarendon is an assistant editor at Wetpaint Entertainment. Follow him on Twitter and Google+!