Below is the first promo for this week's blast-from-the-past episode of Grey's Anatomy, fittingly called "Time Warp." As Interim Chief, Derek restores the hospital lecture series.

As members of the panel, Richard, Bailey and Callie all discuss pivotal surgical cases from their pasts - Bailey reflects on her days as a shy resident, Callie on a polio case, and Chief Webber ventures back to when he and Ellis Grey worked on a patient diagnosed with GRID.

That virus later came to be known as AIDS.

The flashback-heavy hour sheds light on the beginnings of the affair between the Chief (played by J. August Richards) and Ellis (Sarah Paulson) in 1982, as well as 2004 reflections featuring Dr. Bailey in her pre-”Nazi” days and Callie before she was introduced.

Here's the first promo. Sneak peeks and photo gallery to come ...

[video url="http://www.tvfanatic.com/videos/time-warp-promo/" title="Time Warp Promo"] [/video]

Steve Marsi is the Managing Editor of TV Fanatic. Follow him on Google+ or email him here.