It is September 1961, two years after the original Grease gang were Rydell High seniors in the first movie and a new academic year is just beginning at Rydell High School ('Back To School Again'). The Pink Ladies are now led by the beautiful Stephanie Zinone (Michelle Pfeiffer), who feels she has "outgrown" her relationship with the arrogant leader of the The T-Birds, Johnny Nogerelli (Adrian Zmed) during summer break. A new arrival comes in the form of clean-cut English student Michael Carrington (Maxwell Caulfield), the cousin of Sandy Olsson (the character played by Olivia Newton-John in the first Grease movie). Michael quickly becomes smitten with Stephanie, despite the gentle warning of the sole remaining lead character from the first film, Frenchy (Didi Conn), who is returning to Rydell High to get her diploma was told about Michael's arrival in a letter from Sandy and helps Michael get settled into the school atmosphere as Sandy's behest. Michael takes an instant liking to Stephanie, but Frenchy tells him that she will not date him since he is not a T-Bird.At the local bowling alley, a competitive game ('Score Tonight') turns sour due to the animosity between Johnny and Stephanie. Johnny flirts with Stephanie's friend and fellow Pink Lady, Paulette Rebchuck (Lorna Luft), to make Stephanie jealous, and she retaliates by kissing the next man who walks in the door, which happens to be Michael. Bemused by this unexpected kiss, Michael attempts to ask her out the next day at an audition for the school talent show, but discovers that she has a very specific vision of her ideal man ('Cool Rider'). He realizes that he will only win her affection if he turns himself into a cool rider, and begins saving up for a motorcycle by selling completed homework assignments to the academically-challenged T-Birds. Michael buys the bike, fixes it up and spends all his spare time after school learning to ride it.At school a few days later, there is an an unusual, largely interactive biology lesson ('Reproduction') given by new substitute teacher Mr. Stuart (Tab Hunter) over sex education. That evening, a gang of rival motorcyclists called the Cycle Lords (led by Balmudo, who also played "Leo" in the first film and also a rival of the T-Birds) surprise the T-Birds at the bowling alley. Before the fight starts, a lone anonymous biker, wearing all black clothing as well as a motorcycle helmet and dark goggles to cover his face, appears and defeats the enemy gang, performing impressive stunts and leaping over police cars to disappear into the night ('Who's That Guy?'). Stephanie is instantly fascinated with the stranger.The following day at school, Frenchy tells Michael about that motorcycle chase and a strange guy swept Zinone out of her bobby socks. Michael confides in Frenchy he's the one and just as he was about to tell Frenchy his game plan, Zinone and the other Pink Ladies come into the room. That's when Michael attempts to tell Stephanie that he is the "Cool Rider", but becomes tongue-tied. Frenchy notices a patch on Rhonda's nose. (She is also wearing glasses similar to the ones Dinah Manoff wore at one point during the first movie when she played Marty.)In a short comic scene, one of the T-Birds, Louis DiMucci (Peter Frechette), attempts to trick his sweetheart Sharon (Maureen Teefy) into losing her virginity to him by taking her to Michael's uncle's fallout shelter and faking a nuclear explosion ('Let's Do It For Our Country'), but the plan backfires and she runs off in horror.Stephanie is surprised again by the Cool Rider while working at her after school job at her family's gas station, and they enjoy a romantic twilight motorcycle ride. Just as Michael is about to reveal his identity, they are interrupted by the arrival of the T-Birds and the Pink Ladies; before Michael disappears again, he tells Stephanie that he will see her at the talent show, in which the Pink Ladies and T-Birds are performing. Stephanie wonders how the Cool Rider knew about the talent show but fails to deduce it could be a Rydell High School student since only they knew about the show. Johnny, enraged by Stephanie's new romance, threatens to fight the "Cool Rider" if he sees him with her again, and the group has an argument about who belongs to whom. The Pink Ladies exit haughtily, although this has little effect on the T-Birds' innate self-confidence as they stroll off in the night ('Prowlin').At school, Stephanie's poor grades in English lead her to accept Michael's offer of help with her essay on Shakespeare's Hamlet, but although she has warmed to him considerably, he still cannot reveal his double identity.By this point, Stephanie has begun to realize that, despite his shy, bookworm outward appearance, Michael is a kind, good hearted guy who genuinely cares about her. She then slowly begins to discover that she has similar feelings for him, and starts to reciprocate his crush. These events are not lost on their mutual acquaintances, and Johnny, upon seeing them together in a discussion, demands that Stephanie quit the Pink Ladies for his "rep" and subtly threatens that the T-Birds will beat up Michael if she refuses ("Don't damage the rep we won't damage new friends."). Stephanie is visibly upset by this but refuses to quit the Pink Ladies. Although still head over heels for the Cool Rider, interactions with Michael reveal that she has become smitten with him as well, as Michael ponders with himself over his continuing charade he puts out to Stephanie. ('Charades').The night of the talent show, Stephanie and the Cool Rider meet outside the school, but are instantly ambushed by the T-Birds who pursue Michael in a motorcycle chase, with Stephanie and the Pink Ladies following in a car. They pursue him to a closed-off construction site which conceals a deadly drop, and the biker's absence suggests that he has perished below, leaving Stephanie inconsolable thinking her Cool Rider is dead although both the T Birds & Pink Ladies try to convince her that he must have survived and made the jump and will show up again.At the talent show, the T-Birds tie up the competition for their act in the boys locker room and drench them in the showers to ensure their winning. During the Pink Ladies' number ('A Girl For All Seasons'), Stephanie is overcome and stops singing her part and sinks to the stage floor. Oblivious to the audience, she enters a dreamlike fantasy world where she is reunited with her mystery biker in a sort of "biker heaven" backdrop "([Love Will Turn] Back The Hands Of Time)". As her reverie finishes, it appears she has been singing a solo; she is duly named winner of the contest, and crowned the queen of the upcoming luau, with Johnny hailed as king.The school year ends with the graduation luau the next day ('Rock-A-Hula Luau') during which Johnny and Stephanie later engage in another argument while being carried onto the pool in a floating throne. The Cycle Lords suddenly appear and begin to destroy the celebration, but are stopped by the emergence of the Cool Rider, much to the surprise of Stephanie. After roundly defeating the Cycle Lords and leaping over the pool on his motorcycle, he finally reveals himself to all in attendance to be Michael. After his initial shock, Johnny offers him a T-Bird jacket and welcomes him into the gang, and Stephanie finally accepts that she can have "two for the price of one" a Cool Rider and a Shakespeare. All of the couples pair off (Michael/Stephanie, Johnny/Paulette, Lewis/Sharon, Davey/Dolores & Rhonda/Goose), happily at graduation as the class of 1962 (Note: Davey was not a senior so he doesn't graduate then) sings ('We'll Be Together'). The credits start rolling and just like in the first movie, it's in the style of a yearbook.