ShadowFang Keep
Shadowfang Keep is an instance in a Silverpine forest. It is in the southern part of the zone on the coast. The level range for mobs in the instance is 18-27. Most players will want to be in their low-mid 20s before attempting this. Shadowfang is a short straightforward instance with no confusing paths, it can be completed in 60-100 minutes.
Quests
There are a total of five quests that involve Shadowfang Keep.
Paladin
The Test of Righteousness
Rewards: Verigan's Fist
I'm not sure where the paladins have to go for this quest, someone with more knowledge on this should complete a description for what is done with this quest in the zone.
Warlock
The Orb of Soran'ruk
Rewards: Orb of Soran'ruk and Diabolist's Blade
This is just a random drop from some of the werewolves you encounter right after the baron in dining room area.
Undercity
The Book of Ur
Rewards: Grizzled Boots or Steel-clasped Bracers
For this quest you need to pick up a book on a shelf immediatly to your left as you enter the room with the giant wolf Fenrus the Devourer.
Sepulcher
Deathstalkers in Shadowfang
Rewards: Ghostly Mantle
This is an easy quest that you can finish as soon as you get to the courtyard you will see the deathstalker lying on the ground next to the portcullis.
Arugal Must Die
Rewards: Seal of Sylvanas
Simply loot the head of Archmage Arugal the final boss of the instance.
Boss List
Here is a list of bosses in the order you will likely encounter them, with drops from most common to least common.
Razorclaw the Butcher
Butcher's Slicer
Bloody Apron
Butcher's Cleaver
Baron Silverlaine
Baron's Scepter
Silverlaine's Family Seal
Commander Springvale
Arced War Axe
Commander's Crest
Odo the Blindwatcher
Girdle of the Blindwatcher
Odo's Ley Staff
Deathsworn Captain
Haunting Blade
Phantom Armor
Fenrus the Devourer
Fenrus' Hide
Black Wolf Bracers