Dianna Agron and Heather Morris return for Glee's 100th episode... and Cory Monteith is remembered in touching Finn tribute

Dianna Agron and Heather Morris both left Glee last year but now they're making a grand return for the show's 100th episode.

The storyline will feature Dianna's Quinn reuniting with Heather's Brittany and Naya Rivera's Santana for a show-stopping performance.

Fox released the first photos of the eagerly anticipated episode two weeks ahead of its March 18 air date, and they include Quinn paying a visit to Finn's football jersey shrine in the boys' locker room.

Sad and sweet: Dianna Agron will return in Glee's spectacular 100th episode - airing on Tuesday, March 18 on Fox - to pay a touching visit to Finn's football jersey shrine

Sad and sweet: Dianna Agron will return in Glee's spectacular 100th episode - airing on Tuesday, March 18 on Fox - to pay a touching visit to Finn's football jersey shrine

Finn, of course, was played by the late Cory Monteith, who died on July 13, 2013 after an overdose of drugs and alcohol.

Dianna, 27, wasn't asked to participate in the Cory tribute special that aired in early October, but she's making up for that fact now.

The exciting show will see Quinn bopping around with her Glee-ful pals Brittany and Santana while performing as the Unholy Trinity.

Exchange: Heather Morris also returns as Brittany and will have a wistful moment with Naya Rivera's Santana in the classroom

Exchange: Heather Morris also returns as Brittany and will have a wistful moment with Naya Rivera's Santana in the classroom

Unholy Trinity: Brittany, Santana and Quinn perform a riveting number in front of the crowd at McKinley High

Unholy Trinity: Brittany, Santana and Quinn perform a riveting number in front of the crowd at McKinley High

Reunion: Quinn has a tender and somber moment with Puck (guest star Mark Salling) in front of Finn's glass-encased jersey

Reunion: Quinn has a tender and somber moment with Puck (guest star Mark Salling) in front of Finn's glass-encased jersey

A better man: Puck (Mark Salling) has turned his life around and is doing better since Finn's passing

A better man: Puck (Mark Salling) has turned his life around and is doing better since Finn's passing

Memories: Finn was played by the late Cory Monteith, who died in July; the actor is pictured with real life love Lea Michele in a scene from Glee in 2009

Memories: Finn was played by the late Cory Monteith, who died in July; the actor is pictured with real life love Lea Michele in a scene from Glee in 2009

The best friends are dressed in their red and white cheerleader uniforms while revving up the McKinley High School crowd with their super moves and voices, reportedly to the tune of Britney Spears' Toxic.

Dianna is shown in the beginning of the episode flirting with Chace Crawford, who guest stars at Biff McIntosh and ends up in the dumpster covered in spaghetti.

But her character's relationship with Puck, played by the returning Mark Salling, will show some sparks too as they take a quiet moment to reflect in front of Finn's glass-encased jersey.

Look who drops by: Chace Crawford guest stars as a love interest for Quinn and ends up in the dumpster covered in spaghetti

Look who drops by: Chace Crawford guest stars as a love interest for Quinn and ends up in the dumpster covered in spaghetti

Just dance: Brittany and Santana sing and dance out all their differences with Jake (Jacob Artist) and Mike (Harry Shum Jr)

Just dance: Brittany and Santana sing and dance out all their differences with Jake (Jacob Artist) and Mike (Harry Shum Jr)

Taking the stage by storm: Rachel (Lea Michele) and Kurt (Chris Colfer) do what they do best by performing on stage
Taking the stage: Rachel (Lea Michele) and Kurt (Chris Colfer) do what they do best by performing on stage

Taking the stage: Rachel (Lea Michele) and Kurt (Chris Colfer) do what they do best by performing on stage

Save the glee club: Mr Schuester (Matthew Morrison) recruits the original and the new members to save the glee club

Save the glee club: Mr Schuester (Matthew Morrison) recruits the original and the new members to save the glee club

Charms don't hurt: The persistent Mr Schuester is ever so charming as he addresses his club

Charms don't hurt: The persistent Mr Schuester is ever so charming as he addresses his club

Meanwhile, Heather and Naya will have a moment when Brittany and Santana look at each other wistfully while left alone in the classroom.

As fans will recall, their characters were involved in a lesbian storyline.

The episode will also feature Heather and Naya dancing and singing a number with Jacob Artist, who plays Jake, and Harry Shum Jr, who plays Mike.

Up to her old tricks: Sue (Jane Lynch) threatens to topple the Glee-ful gang

Up to her old tricks: Sue (Jane Lynch) threatens to topple the Glee-ful gang

Joining forces: Rachel (Lea Michele) and Mercedes (Amber Riley) celebrate the New Directions glee club together

Joining forces: Rachel (Lea Michele) and Mercedes (Amber Riley) celebrate the New Directions glee club together

What's up: Unique (Alex Newell) and Mercedes (Amber Riley) have a lively chat next to the piano

What's up: Unique (Alex Newell) and Mercedes (Amber Riley) have a lively chat next to the piano

Kristin Chenoweth will be seen sporting a sharp, short hairdo as she celebrates with the New Directions glee club in the choir room.

Matthew Morrison's Mr Schuester will try hard to save the glee club with the help of the originals and the new members, while Jane Lynch's Sue continues to threaten it.

Lea Michele, as Rachel Berry, and Chris Colfer, as Kurt, will do what they do best - sing out their hearts on stage.

Dianna Agron, Heather Morris and Mark Salling aren't the only cast originals morphing back into their famous roles.

The 100th episode will also see the return of Amber Riley as Mercedes, Mike O'Malley as Burt and Romy Rosemont as Carole.

Competition: Mercedes (Amber Riley), Burt (the returning Mike O'Malley) and Carole (guest star Romy Rosemont) watch New Directions compete at Nationals in Los Angeles

Competition: Mercedes (Amber Riley), Burt (the returning Mike O'Malley) and Carole (guest star Romy Rosemont) watch New Directions compete at Nationals in Los Angeles