From Introduction:
A new Star Wars adventure game scenario for use with the Rebellion Era Sourcebook
In this adventure, the heroes experience the Imperial takeover of Cloud City from right in the middle of it all.To escape the clutches of the Empire, they must be brave and resourceful.
The Fall of Cloud City is designed to be used along with the Bespin section of the Rebellion Era Sourcebook. You don’t have to have that book to play, but the background in it will prove helpful in running this scenario.
As the scenario opens, the heroes are tourists visiting the frontierlike Outer Rim Territories.They have come to Cloud City, on the gas giant planet Bespin, to tour the mining facilities and perhaps to take in some of the local color. This adventure takes place toward the end of the movie The Empire Strikes Back, just after Imperial troops have come to Cloud City — but before anyone knows they’re there.
That should be enough to get started.
May the Force be with you.