This is an adventure that has been seen in many a western film. The bad guy has killed someone and been thrown in jail. He is awaiting the marshals or judge to arrive. There is almost always an old jailer who cannot handle the murderer and his gang. The good guy is usually someone who has wanted to be left alone and is somehow convinced to help the jailer. The story progresses by having the gang come and attempt a breakout after some harsh words and threats were made earlier. The bad guy sometimes is broken out of jail and a posse is formed to catch him and the gang. It ends with one of the good guys dying and all of the bad guys losing their lives in a grand shootout. Sometimes there is a love interest in there to showcase a pretty girl. The story can be told better by you.
How do you make the story better? As a GM preparing the adventure I would say that the best way is to take away the predictability of the story. Make sure that the outcome is not always having the bad guys die. If you can craft the adventure to give the bad guys a way to escape their fate or come up with some other ingenious resolution that’s the way to go. Keep the PC’s guessing about the outcome.
The adventure will probably have about 3-5 players that you have to deal with. Try and include them in the protection detail. As the GM you will have to be creative. If a player makes some type of support character, like a merchant, doctor, blacksmith or something similar, find a way to showcase their skills. You can have the bad guy be badly wounded and the doctor needs to keep him alive or the gang is going to lay waste to the town. Maybe the blacksmith is there to repair the old dilapidated jail cell. While he repairs the cell the others have to keep watch 24 hours a day. Try to keep the players involved.
A twist to this story is that the PC’s have to prepare the townsfolk for an “invasion” from the gang. The gang could consist of about 30-40 ruffians. Have the players find ways to defend the town and protect the prisoner. This can be interesting because the players will have to roleplay their interactions with the townsfolk and use their skills to provide security. The players will have to plan their defense. Most other adventures players have played in consist of travelling and a proactive combat attack. This will make the players focus on defense.
As the town and players prepare for the inevitable attack, try and test the defenses as they go up. Maybe there is a couple of the gang that try to sneak in a attack the jail. There could even be the back and forth dialog and threats on the town street. Again play to the PC’s Skills and Disadvantages.
With most adventures it is always a good idea to keep the flow moving and the players active. In this type of adventure it can get boring real quick. Pace and interesting plots will keep the game going. This would be a great one-shot adventure in any genre. You could do the western genre if your group has been stuck in a specific genre for a while. But it can be set in any genre. I ran this in a space genre once and the tech was over the top. The damage rolls were huge and the players were all about doing 10d6 imp damage. Remember the adventure doesn’t have to be about combat. There can be a lot of roleplaying as well. Make it fun.