Found in the very first numbered level (1-1). At the 4th "Clear this area" task (when you first start seeing barrels, and are able to ride a cart), to the right of the house and up a few cliffs, there's a black wolf on a ledge. You need to kill 2 enemies below the wolf, grab a ladder, and use it to propel yourself up to the ledge. Touching the wolf immediately unlocks the achievement.