In Glee season 4, episode 21 “Wonder-Ful,” some familiar faces return to William McKinley High School as Glee pays tribute to the legendary Stevie Wonder.

Fox has released a sneak peek of the episode and you can watch it below.

In the video, we see that New Directions alumni, Mike Chang (Harry Shum Jr), Mercedes Jones (Amber Riley), and Kurt Hummel (Chris Colfer) have returned to Lima and are involved in the current glee club’s Stevie Wonder week.

We see a few snippets of the staging of a group number, with all the students dressed in beautiful bright colors, but no audio for that particular performance. You can listen to all the songs from ‘Wonder-ful’ right over here – which song do you think is being featured in the performance shown in this sneak peek?

Glee Zone’s synopsis of the upcoming episode reads:

Will’s spirits are buoyed after getting several pieces of good news about his students. Having regained his trademark optimism, he tries sharing his positive vibe by assigning the kids the music of Stevie Wonder. Artie gets word that he has been accepted to his college of choice. When he balks at the chance to go for his dream of becoming a filmmaker, it takes some prodding from an unexpected source in order for him to confront the one thing he thinks is holding him back… his mother.

As Rachel prepares for her second callback for Funny Girl, she learns that NYADA policy requires her extra-curricular activity be approved by her instructors, leading to fears her dreams will be dashed by a vindictive and jealous Cassandra July. Plus, it’s old home week as Mercedes and Mike return to Lima to help get the new New Directions ready for Regionals. While the pair takes a few of the gleeks under their wings, Mercedes must contend with disheartening news from Los Angeles, prompting her to make a bold decision about her future. And when Kurt comes home to check up on his cancer-stricken father’s health, Blaine ponders his own future with Kurt and reaches out to Burt for advice.

In the “Wonder-ful” sneak peek, Darren Criss hints at aspects of the above plot for his character, revealing that this episode focuses on dreams that were a long time coming – an album for Mercedes, Funny Girl for Rachel, and, of course, Kurt, for Blaine. Do you think this week’s episode will feature a Klaine reunion?

Glee season 4, episode 21 “Wonder-ful” airs Thursday, May 2 at 9pm Eastern on Fox.