The Lost Wagon
From Diablo Wiki
The Lost Wagon is a Diablo 3 quest first seen in the BlizzCon 2009 demo build. It's a simple "find location" quest that spawns somewhere in The Stinging Winds level, on the surface of Act II, near Alcarnus.
This quest is given by a dying NPC found sitting against a rock near the start of the Stinging Winds surface level. He gives one of those standard "with his dying breath" NPC speeches, gasping about the caravan he'd been part of and the deadly monster ambush he'd just managed to escape. He asked the hero to find the wagon, said there was a great treasure to be taken. (His motivation for wanting a complete stranger to find the treasure was unclear.)
One nice variable to this quest was that the wagon could be either North or East of the dying NPC. The direction changed depending on how the level spawned, and the NPC's quest dialogue adjusted accordingly.
In contrast to the fairly cool broken wagon concept art upon which it seemed to be based, the actual wagon in game was unimpressive. It was just an uncovered wooden wagon with the wheels smashed, and a few boxes and crates lying around near it. No large concentrations of monsters were in the area, and only a few human corpses testified to anything remarkable about it.
The "great treasure" when found was just a chest that didn't drop any more/better loot than other chests.
On the whole, this quest felt unfinished, and might have been buggy in the Blizzcon 2009 demo build; perhaps the chest's treasure wasn't spawning correctly, or there were some monsters who were supposed to spawn in the area who were not?