Bliss Cavendar (Ellen Page) is a misfit in the small town of Bodeen, Texas, with no sense of direction in her life. Her mother, Brooke (Marcia Gay Harden), a former beauty queen, pushes her to enter beauty pageants despite her lack of interest. Bliss and her friend, Pash (Alia Shawkat), dream of escaping, Pash planning on attending an ivy league school in a big city, but Bliss is uncertain as to what she wants for her future. During a shopping trip to Austin with her mother, Bliss encounters three roller derby team members. Intrigued, she and Pash attend a roller derby event under the pretense of going to a football game, where they see the Holy Rollers defeat the Hurl Scouts, a perennially unsuccessful derby team. Bliss tells the Hurl Scouts that they are "her new heroes" and is suddenly drawn to the idea of being in a roller derby herself when one of the Hurl Scouts, Maggie Mayhem (Kristen Wiig) replies, "Well, put some skates on. Be your own hero!"

Returning to Austin, Bliss lies about her age and tries out for the Hurl Scouts, discovering her natural skating abilities in the process.

After realizing she needs to be ruthless in a roller derby, Bliss sees she needs to take charge in other aspects of her life, revealed through various subplots. One involves Bliss's love interest, a lanky young rock guitarist and singer named Oliver (Landon Pigg) whom she meets via her exposure to roller derby. They enjoy a whirlwhind romance and underwater making out, until Oliver leaves for a tour, taking Bliss' T-shirt with him. She later finds a picture of him at a gig with another girl, who is wearing her t-shirt. She breaks up with him following his return, although he vehemently denies anything happened.

Another sub-plot examines Bliss' relationship with her parents, a loving but controlling mother and an amiable but clueless father who seldom opposes his wife's parental decisions, although following her parents' discovery of Bliss' involvement in roller derby (right before the championship roller derby match), she convinces her mother to let her out of a pageant which is at the same time and gets the Hurl Scouts to come get her for the match. Various other sub-plots include her relationship with Pash, and confrontations with a stuck up snob at school. Pash is fine with Bliss' new path, until she gets arrested with an open container of beer while she is waiting for Bliss, who has left to go find Oliver. Eventually, Pash gets together with their manager and forgives Bliss. The movie ends with the Hurl Scouts narrowly losing the championship match and everyone finally getting along; the team chants "We're number two!", the same thing they chanted when they lost their first match (the coach pointed out that there were only two teams involved).

taken from: wikipedia.org