Clay Aiken is revealed as Kenneth's cousin, Mary J. Blige owes Jack a favor and Liz Lemon sings, all seen in the sneak peek for episode 'Kidney Now!'.
Tonight on NBC is the season finale of "30 Rock" which will be wrapped in a musical episode. Jack who has just found his father, is torn at the thought of lending his kidney for transplant and thus arranges a charity concert to gain donation.
NBC still keeps the synopsis under tight wrap but wrote that "Alan Alda, Sheryl Crow, and more guest star as Jack builds a relationship with his estranged father." Posted on the official site is a sneak peek clip where Jack tells Liz he feels bad for not wanting to give his kidney for Milton, Jenna fights in talk shows, and Jack pleads the stars to contribute in the musical.
Apart from Alda and Crow, other musicians such as Mary J. Blige, Clay Aiken, Adam Levine from Maroon 5, and Elvis Costello join the cast as guest stars. Turns out Clay is written as the cousin of Kenneth.
The third season finale of "30 Rock" airs Thursday, May 14 and the half-hour series has been picked up for a fourth season.