The 12 finalist perform Katy Perry's "Firework"' for individuality week; a contender will get one-on-one time with Darren Criss.

Idina Menzel guest mentors; the contenders sing Twisted Sister's "We're Not Gonna Take It"; someone has their first kiss.

The contestants must tap into their vulnerable sides in order to perform a memorable rendition of "Mad World."

The remaining contestants must show off their best moves when they are judged on their ability to dance.

The remaining eight contestants are paired up in a challenge that demands cooperation: singing duets.

The contestants must prove to the mentors that they are tenacious enough to perform a mash-up song.

With only 6 Contenders left it's time to see who can portray their sexuality the best. The winner of this week's challenge will get to work with both Mark Salling (Noah "Puck" Puckerman) and Ashley Fink (Lauren Zizes).

A shock at elimination causes a lot of surprise and disappointment.

Jenna Ushkowitz is on hand in a challenge that appraises the contestants' ability to be believable. The group also performs 'The Only Exception'.

Kevin McHale makes an appearance when the remaining players' generosity is assessed. In addition, the homework assignment of My Chemical Romance's 'Sing' is boosted by the arrival of surprise guests. This week's music video will a mash-up of 'Defying Gravity' and 'Lean on Me'.