More than 40 years ago, two friends decided to collaborate on a new kind of Broadway show, with music from the late 1950s and characters modeled on classic rock ‘n’ roll types. Eventually, Jim Jacobs’ and Warren Casey’s musical had a name: “Grease.” It was the story of Sandy Dumbrowski and Danny Zuko, who spend their summer days and nights together, falling in love. But when autumn comes, Sandy transfers to Rydell High, where Danny goes to school. She’s surprised to find that Danny is not quite the guy she fell in love with.