It's also just great witty writing.
Lets see:
On this episode the crew of Serenity take on a job from a creepy guy called Nishka, to rob a train. The train heist doesn't go as planned, but Mal and Zoey escape by pretending to be a newly wed couple. Inara's respectible status as a compagnion ends up getting them out of trouble. But while there, they learn that they've stolen medical supplies that the people on that planet badly need. Mal has a change of heart, and decides to return the supplies, but makes a powerful enemy in the process.
By golly, is that a plot structure? I think it is! I wish the Mandalorian had a plot structure