Here's the situation: The PCs are investigating a mystery far from town, in the dangerous wilderness. Against my expectations, they decide to go back to town, recruit some help, and return to continue their investigations. The problem is that there's less than two hours left of the session, so there's no time for more random combat encounters in the wilderness. Neither is there enough left of the adventure to leave it for the next session.
I want the players to go back to town as planned, but I don't want to tell them that, "Suddenly, the wilderness is quiet and nothing attacks you." What I want is some way of resolving this dangerous journey in an abstract way that doesn't require much time but still retains the sense of danger and allows the PCs to use their skills to make it safely through. Which brings me to my question:
How can I resolve dangerous journeys without playing out every battle in detail?
Note that this is not about PCs making bad choices; they were powerful enough to survive their first journey through the wilderness, so traveling back is a completely legitimate decision. The problem is that there's not enough time left of the session to resolve any additional battles directly.
Preferably, the answers should be system-agnostic, but if there are system-specific rules that would be possible to adapt, I would appreciate seeing those as well.
Best Answer
So you only have enough time for either finishing off the adventure, or dealing with random encounters, but not both. Therefore any solution requires spending very little time.
Simple Narration
One acceptable way to handle it seems to be to narrate it away. It's entirely legitimate to narrate their travel through the wilderness and cut to the chase, so to speak. Your players won't object, and are even likely to be thankful that you responsibly paced the session so that it had a natural and enjoyable end.
I wouldn't bother with any resolution mechanic, even a simplified one. Sometimes travel in the wilderness is uneventful. Take advantage of that, plus your power as the controller of the world and your responsibility to pace the game well, to just make this time one of those uneventful travels.
If you feel that it is really unrealistic for this trip to be uneventful, mention what trouble they encounter along the way in the past tense, off-handedly, and conveying that "of course" they handled it without any difficulty. For example, encountering and quickly dispatching an already-weakened patrol of orcs can be glossed over in a sentence, giving them your acknowledgement that the PCs are kick-ass and that was nothing to deal with. Lead right into a description that places them about to engage in the final action of the session and you're good. In systems where encounters lead to XP of some kind, I wouldn't hesitate to give them a token amount – unless the resistance was really beneath them.
Alternatively…
Roll For Complications
You don't want to take any time dealing with the travel, but that doesn't mean it has to be meaningless. Taking a page out of Dungeon World, you can call for a roll to test something during the "perilous journey". Decide on a possible complication of the journey that might lead to a mild consequence for them to deal with at their destination.
Perhaps you have them check if they move stealthily, and when they arrive the inhabitants have been warned of the approach of armed people, or not. Perhaps they make a survival check to determine whether they arrive hungry. Perhaps their pack animals were spooked at some point, and an animal handling roll will determine whether they're down one donkey and low on torches and lamp oil as a result.
Whatever complication you think will be interesting, present the potential event, describe the possible consequence, and call for a single test of their abilities to do well. If you like, you can come up with two or three (quickly), and give the players a choice about which one they want to risk on a die roll (they get success on the others free). This is a very quick and flavourful way of making the travel meaningful while concentrating their attention on the important thing: the final action of the adventure.