Glee Season 4, Episode 18: "Shooting Star"
"The members of New Directions are prepping for Regionals, but when an unthinkable event occurs at McKinley High, perspectives are put into order."
Original airdate: Thursday, April 11, 2013 at 9pm on FOX
The exact nature of this "unthinkable event" is still a closely-guarded secret, but rumors are flying that it could be a school shooting. If that does end up being the case, we certainly are in for one heck of an emotional night.
Glee Promo: In-Depth Analysis of Season 4, Episodes 18 and 19