Trouble in Skyrim

Details
Talk to Farkas to get this quest. This is one of three possible repeatable quests Farkas will offer the Dragonborn after reaching a certain point in the Companions quest line.

The quest seems to be completely randomized each time. A few examples are listed below.

Possible objectives

 * Kill the leader of Geirmund's Hall
 * Kill the leader of Halted Stream Camp (Bandits)
 * Eliminate the Falmer in a cave northwest of Whiterun
 * Kill the leader of Clearpine Pond
 * Kill the leader of Shimmermist Cave
 * Slaying vampires in Bloodlet Throne
 * Kill the leader of Redoran's Retreat
 * Kill the leader of Broken Fang Cave
 * Kill the leader of Brittleshin Pass
 * Kill the leader at the Wreck of the Winter War, located Northeast of Windhelm
 * Kill the leader of Haemar's Shame
 * Kill the leader of Halldir's Cairn
 * Finding a lost iron axe in the Lost Echo Cave, west of Solitude
 * Killing the mage threat at Rannveig's Fast
 * Kill The Bandit Leader in Valtheim Towers
 * Kill The Forsworn Witch in a cave south of Rorikstead
 * Kill Strix, leader of the Glenmoril Witches west of Riverwood
 * Kill the Spriggan leader and clear Shadowgreen Cavern
 * Kill the leader of Yngol Barrow
 * Kill the leader of Yngvild Barrow
 * Intimidate Arcadia in Whiterun
 * Intimidate Jervar in Whiterun
 * Kill the Spriggan leader of Peak's Shade Tower
 * NOTE: If you clear this cave out prior to accepting this quest from Farkas, the Spriggan leader will not spawn again, only the normal spawns. There is also no way to abandon the quest. However, the cave will re-spawn upon re-entering the cave, including the chests.
 * Kill the leader of the Tovald's Cave, north of Riften and south east of Windhelm.
 * Kill the leader of Dead Crone Rock
 * Kill the leader of Broken Oar Grotto
 * Kill the leader of Knifepoint Ridge
 * Kill the leader of Serpent's Bluff Redoubt
 * Kill the leader of Harmugstahl
 * Kill the leader of Silent Moons Camp
 * Kill the leader of Valtheim Keep
 * Kill the leader of Rannveig's Fast
 * Kill the leader of Druadach Redoubt
 * Kill the leader of Deepwood Redoubt
 * Kill the leader of Moldering Ruins
 * Kill the leader of Orphan Rock
 * Kill the leader of Damphall Mine
 * NOTE:  If you have already killed the hagraven in the quest The Blessings of Nature, exiting the room and then speaking to Farkas again should complete the quest. If not, try traveling to Orphan Rock and back again to speak to him.

Return to Farkas once the mission is complete for a reward of 100-300.