Meredith Grey's condition is worsening.
The latest clip released for Grey's Anatomy Season 17 Episode 4, airing Thursday, December 3, confirms as much.
But what it also reveals is that Ellen Pompeo's alter ego will be faced with another figure from her past.
If you watch Grey's Anatomy online, you know Mer has been seeing her deceased husband, Derek, every time she closes her eyes after contracting COVID-19.
We know Patrick Dempsey is back for multiple episodes, but we don't know which other face could be returning to greet Meredith in her dream-like state.
The series has featured plenty of death throughout its time on the air, and Meredith has lost countless people.
As a result, there are so many former characters that could stage a comeback to help Meredith during this difficult time.
We know she was hurting after Alex left on Grey's Anatomy Season 16, but that would assume the beach in her mind would allow her to meet with people who are still technically living.
We witnessed her struggle to allow Alex to make decisions on her behalf during Grey's Anatomy Season 17 Episode 3, suggesting that she still thinking about him.
Given that there was a lot of mystery surrounding the way Justin Chambers exited the series, we're inclined to believe it will not be him, but then again, we never thought Patrick Dempsey would return.
It could also be one of Meredith's parents, George, Cristina, Mark, or even Lexi. Like we said, Mer has lost a lot of people during her time on the series.
The trailer also teases Meredith's condition getting worse, which is not a good sign. COVID-19 is an unpredictable virus, and people can be fine one minute, and in danger the next.
The series is doing a great job of highlighting that.
Don't expect any details to leak out about the return ahead of the episode. Much like Dempsey's comeback, the details of this character's appearance will have been kept well under wraps.
It's rare for TV shows to genuinely surprise audiences these days, but that's what's making Grey's Anatomy Season 17 must-watch TV.
Have a look at the clip below and hit the comments with your theories.
Paul Dailly is the Associate Editor for TV Fanatic. Follow him on Twitter.