The party went to loot the bandit camp even though the NPC had already killed everyone there, and aside from some minor bits of loot they found a map showing a plan to attack the little village.
"Well, it's a good thing we found this. We can use it as proof that these were the goblins responsible for the sabotage."
The map showed that the river was, in fact, just to the north, so they headed south to follow the other tracks the ranger had told them about, and eventually came to a cliff face with a cave in it. Obviously, they had to enter.
While walking along, they discovered a secret door in the side wall, and decided to head that way first. It turned out that the secret door was just a shortcut and not anything that led to an actual secret area or anything, but they tooled around the cave for a while, killing random goblins and gricks and gnolls and other monsters, until eventually they came to a temple to Yeenoghu.
Priestess: "Ah, the sacrifices have arrived!"
...she didn't live out the round after saying that. Her mage went down the next round, and then the party sat back and wore down her fighter. Flawless victory!
After cleaning out the treasure room (not literally, the place was a pigsty) they headed back to town to report success. "See? And they were planning to attack your town, too. Good thing we killed them all."
The gnoll army attacked the town the day after they left.
last session | next session
Actually, the last bit went:
GM: "Two days later, you're awoken in the night by howls surrounding the town..."
Lazar: "Wait, why are we still in this town two days later? Weren't we heading for the city?"
Me: "Well... maybe we had to stay here to sell everything?"
Lazar: "But we couldn't sell much of anything here except for maybe the nonmagic equipment. There's no way we'd still be here two days later."
GM: "Well, fine. Then I guess there's no one left to save the town from the gnoll army that wipes it out."
Me: "Oops! I guess our work here is done."