After completing "Reign of the Black King", talk to Deckard Cain again. He is standing near the New Tristram Inn. He is asking the stranger questions, wants to learn every detail the stranger can remember. The stranger mentions falling, fire, and a sword of great power. It was once a part of him, but it shattered into three pieces as he fell. Deckard Cain believes it is vital that we find those pieces. He believes the sword made whole will restore the stranger's memory. Leah mentions that the goatmen are rampaging through the fields, and suspects the sword has something to do with this behavior. Deckard agrees. Just as the dead rose around the stranger, the sword pieces drove the goatmen to madness.

You receive your next Act I quest:

Sword of the Stranger
Go to the Fields of Misery

Spend some time in town, buying, selling and restocking. Buy some health potions from the innkeeper, you will probably need those. You should also go over all the items in your inventory, to make sure your character is wielding your most powerful available weapons and armor. Also, check your character screen to make sure you have trained all the latest powers. When you are ready to go, head to the New Tristram Waypoint, and choose "Cemetery of the Forsaken" as your destination. Then, head northeast, following the yellow arrow. Pass through a big gate and enter the Field of Misery. Your objective now is to search for the Khazra Den in the Fields of Misery.

Enemies you encounter here include beasts such as Moon Clan Warriors, Plague Carriers, and a gigantic Savage Beast.

Look for beacons such as a Fortune Shrine. Using the fortune shrine will give you a blessing that grants you +25% magic and gold find. There are also chests to be found in this area.

The exit you seek will be found to the northwest. To the northeast, there is a Sheltered Cottage, or Pillaged Home. A bag lays in front of it, which contains a lore item: Wandering Tinker's Diary. Inside the Tinker's Hovel, there is a merchant, the Wandering Tinker, who can sell some rare and useful items.

This zone also has a dungeon called:
Scavenger's Den

This dungeon has two levels, Scavenger's Den Level 1 and Scavenger's Den Level 2. It has monsters such as Burrowing Leapers, Quill Demons and Plague Carriers, and sometimes elites such as Loathus, Thrall of Azmodan (Jailer). In the second level of Scavengers Den you can usually find a Resplendent Chest with some great loot in it.

In the Center of the Fields of Misery, you will also find a Decaying Crypt. You should explore this dungeon, as it contains many treasures, as well as helping you get the "No Stone Unturned" achievement. In Level 2 of the Decaying Crypt, speak with Willa Rathe to begin an event:

The Family of Rathe
Kill the Rathe Family

You need to help the ghost of Willa Rathe put her family to rest. This is a simple side quest consisting of three bosses to kill: Father Rathe (Defiled Patriarch), Mother Rathe (Defiled Matriarch), and Little Jebby Rathe (Defiled Progeny). After you kill all of these bosses, talk to Willa Rathe to complete the event, and get some XP and a rare item.

After you are done exploring the Fields of Misery, locate the cave, and enter Khazra Den to advance in the quest.