In season 4 episode 20 of "Glee" Sarah Jessica Parker makes her return to the show on Thursday night in the episode "Lights Out." Parker plays Vogue.com boss Isabelle Wright returning to recruit intern Kurt to help out with a company sponsored event to help raise money for charity.

Meanwhile Mckinley High experiences a massive power outage, leaving the glee club with no way to rehearse. Will steps in to turn the unfortunate situation into a challenge for the students. Will encourages the students to push the limits of their talent and sing acoustic and acapella style.

The New Direction crew will be heard singing medleys of songs such as "Everybody Hurts" by R.E.M, "For the longest Time" by Billy Joel, "You've lost that Lovin" by The Righteous Brothers, and "We will rock You" by Queen.

Meanwhile in New York Rachel, Kurt, Santana, and Isabelle can be heard singing "At the Ballet" from the Broadway musical, "A Chorus Line."

In an ironic twist the character Sue will be heard "Little Girls" from the Broadway musical Annie. In real life Jane Lynch will play the coveted role of Miss Hanigan in Annie on Broadway in New York City following the end of season 4.

Lynch's character Sue now has a new career as a hardcore aerobics instructor at a local gym and Blaine will spend the episode searching for the truth behind Sue's termination from Mckinley High.

To hear full versions of the songs that will be performed by the "Glee" cast in season 4 episode 20, click here.

Click Here to see spoiler shots of the upcoming episode of "Glee" titled "Lights Out."