Shelby Corcoran returns to the halls of McKinley High. Meanwhile, Mr. Schuester initiates a boot camp for some of the members of New Directions.

Emma gets a visit from her parents; Mike Chang's parents get involved when his grades aren't up to their standards.

Irish exchange student Rory Flanagan arrives at McKinley High. He is living at Brittany's house, and she thinks he's a leprechaun. Mercedes starts recruiting for Shelby's new glee club, and Sue's run for congress picks up steam.

The school musical West Side Story is readied for performance, with Artie as lead director. Finn meets with a football recruiter, whom Coach Beiste gains as an admirer. Kurt and Blaine reach a new, physical stage in their relationship, as do Rachel and Finn in theirs.

Congressional hopeful Sue Sylvester starts a smear campaign to ruin the candidacy of her biggest rival. Puck falls in love, and glee club directors Will and Shelby encourage some friendly competition between their clubs

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 Mike and encourages him to pursue his dream while McKinley prepares to host the big sectionals performance.

Artie is asked to direct and produce a Christmas special for the local PBS station, while some of the New Directions learn the 'true' meaning of Christmas.

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 Glee Club does disco in a tribute to Saturday Night Fever.

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.

Tina's head injury from falling into a fountain leaves her seeing her fellow singers and other people at McKinley High in a new way as rehearsals continue for the glee club's Nationals performance.

The glee club travels to Chicago, Illinois, to compete in Nationals against the best show choirs in the country, including Vocal Adrenaline, for celebrity judges including Lindsay Lohan and Perez Hilton.

The William McKinley High School class of 2012 graduates, and the glee club bids farewell to its graduating seniors.