someone has been attacking caravans on the road and stealing supplies. I wonder where they are keeping all of that loot and supplies. Lets check that cave over there, might be a clue of some kind.

Bandits have tried there best to hide their secret stash, Hoping that no one finds the hidden cave with all the loot they've been stealing. perhaps they leave some comrades in there to protect what's theirs, archers can set up and try to bottle neck any intruders on the bridges, as they slowly fall back to their last stand. Anyone knocked into the rushing water would be battered on the rocks and washed down steam and out of the cave.