'Glee' stars Lea Michele, Cory Monteith and Amber Riley are set to guest-star in 'The Simpsons'.
The stars will play their 'Glee' characters, Rachel Berry, Finn Hudson and Mercedes Jones.
The episode, which is due to air in the US on 26 September, will be called 'Elementary School Musical' and will see Lisa meeting the characters at an arts camp.
