It is September 1961, and a fresh academic year is dawning at Rydell High School. The Pink Ladies, now under the leadership of Stephanie Zinone, feel the shifting dynamics of relationships. Stephanie realizes she has "outgrown" her romance with the cocky leader of The T-Birds, Johnny Nogerelli, during the summer break. Meanwhile, a new student, Michael Carrington (/actor/maxwell-caulfield), who is also the cousin of Sandy Olsson, arrives and quickly develops a crush on Stephanie. He receives a heads-up about her from Frenchy (Didi Conn), the returning character from the first film, who is completing her diploma and provides Michael with advice as instructed by Sandy.
Michael awkwardly pursues Stephanie, but Frenchy warns him that she won’t date anyone who isn’t a T-Bird. The tension escalates during a competitive night at the local bowling alley, where a game spirals into conflict over Stephanie and Johnny's relationship. Determined to make her jealous, Johnny flirts with Paulette Rebchuck (/actor/lorna-luft), while Stephanie retaliates by kissing the next guy who walks in, which happens to be Michael. Surprised by this unexpected twist, Michael seizes the moment to ask her on a date during auditions for the school talent show, but he learns she has a specific type in mind.
Wishing to win her over, Michael decides to transform himself into a "cool rider" and begins saving up for a motorcycle. He starts selling completed homework to the other academically challenged T-Birds. After successfully acquiring a bike and dedicating himself to mastering motorcycle riding, the T-Birds encounter a rival gang, the Cycle Lords. However, a mysterious Cool Rider, clad in black, appears and saves the day, capturing Stephanie's intrigue.
At school the following day, Frenchy informs Michael about the biker's daring stunt and, as he tries to confess his identity, Stephanie and the Pink Ladies enter the room. Michael struggles to tell her that he is the Cool Rider, further complicated by a humorous subplot involving Louis DiMucci (/actor/peter-frechette) trying to trick his girlfriend Sharon (/actor/maureen-teefy).
As the relationship between Michael and Stephanie begins to deepen, she asks him for help with her Shakespeare essay. Despite everything drawing them closer, Michael still can’t reveal he is the Cool Rider. When the T-Birds threaten him if Stephanie doesn’t quit the Pink Ladies, she faces an emotional turmoil, yet she stands her ground.
The night of the talent show brings a climactic twist as the Cool Rider and Stephanie meet, but they are ambushed by the T-Birds, leading to a dangerous motorcycle chase that ends in what seems to be tragedy for Michael. Stricken with grief, Stephanie believes her Cool Rider has perished, while the T-Birds and Pink Ladies attempt to comfort her with hope of his survival.
During the talent show, a heart-wrenching moment occurs where Stephanie is lost in a dreamy fantasy about her Cool Rider, culminating in a solo performance that wins her the contest and makes her queen at the upcoming luau.
Finally, at the graduation luau, filled with tension, Johnny and Stephanie argue as the Cycle Lords crash the party. In a stunning revelation, the Cool Rider emerges once more, ultimately revealing himself to be Michael. Following his daring feats, Johnny acknowledges him warmly, offering him a T-Bird jacket and acceptance into the group. The film wraps up with all the couples pairing off, establishing a celebratory note for the end of the school year.
