Credit: Video Still

Based on this preview, it looks like things are going to get majorly intense on Grey's Anatomy Season 9, Episode 20: "She's Killing Me" (April 4). Yes, even more intense than a gas tanker explosion.

In this preview, we see that there's a mysterious outbreak at the hospital that leaves at least one person dead, and raises a lot of questions about what went wrong. Meanwhile, it also looks like Bailey tells Meredith "you have tested positive." Is that related to Alzheimer's or is it just tricky editing?

Here's the official synopsis of the episode:

Upon receiving some unsettling news, Meredith and Derek take preventative steps for their children's future; a group of Syrian doctors arrive at Grey Sloan Memorial Hospital for a crash course in basic surgical skills that they plan to apply in the field; and April decides to come clean to Matthew regarding the truth about her virginity. Meanwhile, multiple pre-op patients develop infections, causing one doctor to wonder if she is at fault.

Check out the preview!

Credit: YouTube Photo: Grey's Anatomy Season 9, Episode 20 Preview: Does Meredith Have Alzheimer's?

Catch the next new episode of Grey’s Anatomy on Thursday, April 4, 2013, at 9 p.m. ET/PT on ABC.

Rebecca Martin is an editor at Wetpaint Entertainment. Follow her on Twitter @BeccaDMartin.