STAGE TUBE: Sneak Peek of GLEE's 'I Am Unicorn'

Tonight's episode of GLEE, titled 'I am Unicorn,' will mark the return of Tony winner Idina Menzel as Rachel's mom, Shelby Corcoran. During the episode, Lea Michele and Idina Menzel (Rachel and Shelby) sing "Somewhere," Darren Criss (Blaine) sings "Something's Coming," and Chris Colfer (Kurt) sings "I'm the Greatest Star." Catch a clip from the episode below!

GLEE follows an optimistic teacher who - against all odds and a malicious cheerleading coach - inspires McKinley High's Glee Club to conquer the world one singing competition at a time. GLEE stars Dianna Agron, Chris Colfer, Jessalyn Gilsig, Jane Lynch, Jayma Mays, Kevin McHale, Lea Michele, Cory Monteith, Matthew Morrison, Amber Riley, Mark Salling and Jenna Ushkowitz.

GLEE is produced by Ryan Murphy Television in association with 20th Century Fox Television. Ryan Murphy, Brad Falchuk and Ian Brennan are co-creators of the series. Murphy, Falchuk and Dante di Loreto serve as executive producers, while Ian Brennan serves as co-executive producer.

To date over 33 million Glee songs have been digitally downloaded, with over 10 million albums sold worldwide. Glee scored three consecutive #1 releases with Glee: The Music, Volume 3 Showstoppers, Glee: The Music, The Power of Madonna and Glee: The Music, Journey To Regionals. The RIAA has certified Glee: The Music, Volume 1 Platinum (sales in excess of 1 million units) as well as Glee: The Music, Volume 2, Glee: The Music, Volume 3 Showstoppers and Glee: The Music, Volume 4 Gold (sales in excess of 500,000 units).