An entry into the Merry Band category of the Colossal Castle Contest. This year I'm basing all of my CCC entries on The Peleg Chronicles book series.
This build would actually take place before the events of the series.
Before being banished from the Dwarven Brotherhood, Squilby made a large fortune off of his clever heist operation.
Along with a few other dwarves of questionable repute, he set up traps in several old tunnels that ran underneath or near prominent roads.
One of the group would lure passersby into the trap by offering a large reward to them if they'd give him a hand carrying his chest full of gold and jewels.
When they left the road to help (or if less than honest to take possession of the seemingly unguarded treasure), they fall into the tunnel below.
A dwarve hiding near the road would 'convince' anyone who caused trouble into the trap.
If the fall didn't render them unconscious, a few dwarves standing by with cudgels knocked them out. Then they'd strip the victim of anything of value and
deposit him back aboveground via a tunnel exit.
(Click to enlarge)