This is a sabotage quest given by Gil McMartin at -923, -48, 14 in The Commonlands. All of these quests take place within the City of Freeport. The quickest method to reach the city is by clicking on the manhole to The Thieves' Way at -1249, -84, 120 in the Commonlands. Inside the Thieves' Way use the grates to head into North, West, East or South Freeport.
You are asked to overturn 5 merchant carts to avenge the looting of slain Qeynosians. You have 20 minutes to do so.
The carts can be found in Freeport.
East Freeport: Around the shops and the banker area on the docks.
South Freeport: South of Freeport Block and Tackle and on the dock.
West Freeport: Around the stables, by the barber, and near the merchants west of the Freeport Reserve.