Location: Boklad
Petitioner: Eloise
Unlocked: Complete Cloak and Dagger
Reward: 50 Wyrrite, 1 Meteorite, 1 Black Blood, 50 Renown, 1,200 gil
To unlock this side quest you need to complete the majority of the main quest Cloak and Dagger. This involves traveling to Tabor, south of the Krozjit Echoes, and then down the Gilded Path. Once you exit the Gilded Path you'll unlock several side quests, including Trading Places.
The petitioner for Trading Places is Eloise, the owner of the Crimson Caravans in Boklad. She's standing with Theo out front of the Crimson Caravans, and she needs Clive's help. Apparently the number of masterless Bearers has risen substantially, and she wants to relocate them to an abandoned village... or at least abandoned by humans. There are plenty of monsters that need to be slain.
Travel to the Laetny's Thread Obelisk and take the first path on your right, which used to be blocked by a gate. A Porter has opened the way for you. This will take you into the Drakos Deep, a path that connects with the Krozjit Echoes. Head south, fighting off some Goblins, until the path splits. You'll see an Item on your left, next to a cliff. The path to the right will take you to your destination... or you could just hop off of the cliff and get there a bit earlier.
The Abandoned Fishing Village is full of Feral Hounds which shouldn't give your team any trouble. Take out most of the hounds and a squad of Helldivers will show up next, along with more Feral Hounds. This second set of enemies is slightly more difficult, but still no big deal. Wipe them out to end Sharp Fangs and Bloody Hides.
You can poke around the Abandoned Fishing Village a bit, if you like, but there's not much to see besides Items. Head back to Boklad and you'll catch a quick cut scene when you approach the Crimson Caravans. Speak to Eloise after the scene is done to complete the quest. (Though the chances that you're done with Eloise and Theo are pretty low.)