Grey's Anatomy has had some nutty storylines before, but nothing has stretched the limits of plausibility quite as much as "Izzie does the deed with Dead Denny." Not even the non-melty icicle that stabbed Cristina!
As you can see from sneak peek of next week's episode above, Izzie still appears to be 100 percent off her rocker.
So what the bejeezus is going on? It's time to find out: Is Isobel Stevens, M.D. (Katherine Heigl), crazy, grieving, fantasizing or, quite possibly, all of the above?