The action of which Andrew Lloyd Webber musical takes place in a child's dream?

"Starlight Express" is a 1984 British musical, with music by Andrew Lloyd Webber and lyrics by Richard Stilgoe. It tells the story of a young but obsolete steam engine, Rusty, who races in a championship against modern engines in the hope of impressing a first-class observation car, Pearl. Famously, the actors perform on roller skates.

"Starlight Express" is the ninth-longest-running West End show and the most successful musical in Germany, where it has been performed in a purpose-built theatre since 1988, holding the Guinness World Record for most visitors to a musical in a single theatre.

The musical starts with a young boy who falls asleep as he plays with his toy trains. In his dreams his train set magically comes to life and the various engines compete to become the “Fastest engine in the World”! The underdog, Rusty the Steam train, has little chance until he is inspired by the legend of the “Starlight Express” and ultimately defeats his arch-rivals Greaseball and Electra before going on to win the hand of the lovely first class coach, Pearl.