I GMed a game once. The group were another group of former Browncoats, and the timeframe was concurrent with the beginning of Firefly. The group was desperate for money and running out of food and fuel when they were contacted by Adelai Niska. He offered to pay them a nice chunk of money, and provide them all the supplies they'd need to perform the job he had for them.
He wanted them to travel to a small backwater town and retrieve the contents of a deposit box at a bank the planet. They had nine days (and their trip was 96 hours in each direction, granting them approximately 2 days on the surface to accomplish their mission if they wanted to be on time), but for every hour they were late they'd lose 100 credits out of their 1000 credit reward. They also were promised all the loot they could carry away... Niska was only concerned with the deposit box.
There were a few other complications to be had, other than just the time limit:
1) On the way there, they were harassed by the Alliance. They were inspected fairly thoroughly because of how they handled the conversation (they made the Alliance inspector feel rushed, so he thought there had to be something they were hiding. The ship was clean, but time was wasted.
2) When they got there, they discovered the owner of the safety deposit box in question was a war buddy of one of the characters (the captain of the ship)
3) There was another gang also after the box, with significantly more... brutal methods.
Fighter: "I can kill a guy in one turn."
Cleric: "I can kill a guy in half a turn."
Wizard: "I can kill a guy before my turn."
Bard: "I can get three idiots to kill guys for me."