The 100th episode will center on Jane Lynch's principal Sue Sylvester, who after years of disdain for the New Directions and Matthew Morrison's Will Schuester, finally succeeds in ending the glee club in Lima. Many original cast members -- Heather Morris (Brittany), Harry Shum Jr. (Mike), Mark Salling (Puck), Amber Riley (Mercedes), Dianna Agron (Quinn) and Kristin Chenoweth (April), the latter of whom won an Emmy for her guest turn -- will return to say their final goodbyes to Will and each other in an episode that is said to be very moving.
Chenoweth will be singing a Pink song with Matthew Morrison (Will) on the episode. Paltrow will appear as her GLEE alter ego, substitute teacher Holly Holiday.
The two part episode will air March 18 and March 25.
The Fox musical will then do several consecutive episodes set in New York City, centering on Rachel (Lea Michele), Blaine (Darren Criss), Kurt (Chris Colfer), Sam (Chord Overstreet) and Mercedes (Amber Riley) and potentially other co-stars.