Its fall and that means back to school for the students and faculty at McKinley High. The New Directions clan returns after a devastating loss at Nationals, so Mr. Schuester assigns a project to get them back on track. Meanwhile, Sue Sylvester starts her congressional campaign.

New Directions faces a shake up when Shelby Corcoran (special guest star Idina Menzel) comes to McKinley High and Rachel has to deal with the return of her biological mother. Meanwhile, Kurt starts his run for class president with the special help of Brittany.

Rusty and Rose Pillsbury pay Emma a visit and we get a sneak peek into her deep rooted issues. Meanwhile, Mike Chang struggles with his grades and his parents step in to make sure he stays on track.

Mercedes tries to convince Santana to join Shelby's all-girl glee club. Meanwhile, Brittany's family takes in Irish exchange student.

The opening night of the school musical is approaching and the two leads are contemplating taking their relationships with their perspective significant others to the next level. Meanwhile, a scout visits McKinley High which could influence Finn's future.

Harmony, the girl Rachel met at the NYADA mixer, comes to McKinley High to terrorize Rachel into not applying to the program.

As the race for McKinley High President comes to an end, someone is caught trying to fix the results. Meanwhile, Coach Beiste gets up the nerve to challenge Sue Sylvester and things get complicated for Puck and Quinn.

In an attempt to recruit a few more members, Finn tracks down former teammate Sam Evans and convinces him to come back to the glee club. Tina comes to the defense of Harry and encourages him to pursue his dream while McKinley prepares to host the big sectionals performance.

When New Directions is asked to perform at two different events - on the same day, at the same time - they have a tough decision to make. Will they choose correctly and spread Christmas cheer, or will their ambition get the best of them?

When Will tries to plan a special surprise for Emma, he enlists the glee club to help him sweep her off her feet. Meanwhile, Becky sets her sights on Artie, and Finn makes an announcement about his life plans after high school that surprises the glee club.

In a special episode celebrating the music of Michael Jackson, the rivalry between New Directions and the Warblers intensifies en route to Regionals. Meanwhile, Kurt and Rachel receive news regarding their admissions process at NYADA, and things continue to heat up between Sam and Mercedes.

Will assigns the glee club a Spanish singing assignment, and enlists the help of his musically-inclined night school teacher. Meanwhile, Rachel spills the beans to Kurt and Mercedes on Finn's marriage proposal, and Mercedes has love complications of her own.

In honor of Valentine's Day, Will challenges the New Directions to find and perform the world's greatest love songs. Meanwhile, Rachel's two dads Hiram and LeRoy Berry pay a visit to McKinley High.

Things heat up as the New Directions go head-to-head with the Dalton Academy Warblers at Regionals.

Much to Blaine's chagrin, his big-shot Hollywood actor brother, Cooper, comes to visit.

The New Directions pay homage to the movie "Saturday Night Fever" by grooving to disco-infused dance numbers.

The glee club pays homage to a true icon when they cover Whitney Houston's greatest hits. Meanwhile, Emma and Will are one step closer to their dream wedding.

Rachel and Kurt finally get their chance to audition for the New York Academy of the Dramatic Arts. Meanwhile, Puck makes a decision about his future after a meeting with his father.

Brittany goes into high gear as class president to spearhead the prom. Then, after prom king and queen nominations are announced, the kids kick into campaign mode, and some of the outcasts organize a rival celebration.

As the countdown to graduation continues, the kids of New Directions prepare a high-concept routine for Nationals. When Tina bumps her head, the world of New Directions is turned upside down in her eyes. Then, the New Directions perform at Nationals for celebrity judge Lindsay Lohan.

Nationals and graduation approach, and while the glee kids prepare their high-concept routine, Tina bumps her head and sees New Directions from a new angle. Lindsay Lohan (playing herself) is a guest judge.

Graduation is finally here, as McKinley High's class of 2012 looks to the past and present, while contemplating the future.