Haunted Valley: The Curse and The Tower

The Valley was cursed many years ago.  

The Cursed Tower
The East Wood, many centuries past.
An ancient road ran through the forest in those days and was guarded by a tower, the home of two brothers, knights. The older brother was a prideful man, a powerful warrior. The younger was also a skilled warrior but was kind and merciful. They argued as brothers are wont to do. For years they guarded the road from bandits, protecting travelers and keeping law and order in the land. The elder brother grew ill, sick and half mad. How this occurred is lost to time, later tales were unclear. In the end it drove him to madness and he attacked his brother, slaying him in a fevered rage before he took his own life. But fate was not done with the mad knight. For his actions he was cursed to rise as a Death Knight. He soon began to haunt the road despoiling and killing those he had been charged to protect.

A companion of the brothers, a priest, returned to his home from a pilgrimage and learned of the attacks from the tower. He entered the tower with his own key of silver, given freely by his former companions in trust, to discover what had befallen his allies. Soon he found his friend the younger, a pile of moldering bones and, to his horror, the heart of the noble brother, intact and still beating. Alerted to the priest's presence the older brother, the cursed Death Knight, came forth from his upper chambers. In a fright the priest fled, barely escaping the dread knight. Leaping through the door he turned and locked it with his silver key and layed a powerful curse on the Death Knight, locking it into the tower for eternity.

The priest bound the knight, the knight's actions and presence infected the tower, the tower's presence slowly cursed the valley over the centuries with darkness and evil, drawing madness and fell creatures to the valley. Until the Death Knight is destroyed the valley remains under the sway of evil.

The priest, wracked with guilt over his failure to completely cleanse the evil and physically broken by the laying of the binding curse, stayed to watch over the valley and the village which had sprung up in the years since. He slowly wasted away and died, unable to bring himself to enter the tower and freeing is friend's souls for fear of releasing the creature trapped within. To keep the Death Knight bound and protect the valley's residents he instructed the village priest to bury him in a secret grave with the silver key to the tower.

The tale survives all these centuries later as bits and pieces of legend and folktale. Most of the details were intentionally hidden by the old priests and ancestors of the villagers. Forgotten and buried away.

The location of the tower has been lost to the ages. The evil seeping from it twisted the Darken Wood around the tower aiding in hiding it from those who enter the Eastern Woods. The tower itself fades out of reality, only visible and accessible on the night's of the full moon and the anniversary of the locking of the tower. Eventually the curse grew strong enough that those who did stumble upon it (such as Old Svalovich) forget the location soon after seeing it (1d6 hours). They do often dream of an old tower in the woods but cannot comprehend why upon waking. Another insidious property of the curse is that those who dwell in the valley for one full month (full cycle of the moon) must make a Saving throw. If they fail they will be compelled to dwell within the valley, trapping them in the curse with no desire to return to their true homes. Those who are born in the valley automatically fail this Saving throw when they come of age. They are trapped in misery.

• To lift the curse the lore of the tower must be discovered. 
• The location of the tower and the secret grave of the priest with the silver key must be found through the lore and clues. 
• The key must be used to open the tower, the eternally beating heart of the noble brother must be staked to release his soul, and the Death Knight must be destroyed. 
• Once this is done the pall which hangs over the valley will be lifted and the evil creatures in it will soon leave or fade away. 

Life will become normal for its inhabitants. They will be free to stay or leave.

Information Sources
Here are several possible sources of information for the DM to dole out to his players to solve the mystery of the Tower and Valley. I've kept it vague in many areas for you to rearrange and place clues as needed.

This will probably be reorganized and edited as I go. We shall see.

Tavern: 
Rumors and half truth information about the broken witch coven, ghosts, sightings. Lots of speculation and red herrings here. One juicy find would be the mention of a few people having similar dreams, especially some older hunters over the years, of a lost tower in a forest.

Church records: 
Letters, journals, records about ghosts, demons, and goblins in the valley. Enough to seed a few missions into the forests and lead to encounters with entities.
A few letters about bad dreams and tower sightings.
An ancient broken stained glass window in the cellar showing two knights in a forest tower with a key and a heart between them..

Lore twisted over time, Children's Rhymes:
(passed down, bits come may come in dream to sleepers, may be carved on trees, stonewalls, etc)

The Curse has been laid upon our good Town
The Witch and Wolves and Ogres gather round
Surrounded by Darkness, alone in our Town
We wait for te Evil to swallow us down

The Knight in his Tower
He broods all alone
for a Brother he lost
Long long ago

Find the Key, lift the Spell
Find the Heart of the Brother who fell

Mad Gaston;
Witches, Ogre, The Black Rider, Old Svalovich creeping, the journal. He has seen them.
Old Svalovich's Journal: Location of Lost Tower. In his madness Gaston believes that he must keep the tower a secret. He will not reveal what he knows short of charming spells, extreme torture, etc. If the journal can be found in his hovel it is written in legible French and Latin.

Mother Toad:
Information on remedies, superstitions, charms. Basic information on the witch coven, leaders, meeting place, etc. Knows of many who dream of a lost tower somewhere in the valley. Believes Gaston may know more but he won't tell. She may have the knowledge to show the investigators how to summon a ghost via the creation of ghost chimes or spirit candles. 

The Midnight Cat:
The witch coven, location of the alter hiding place, ghosts, information on the Guard Captain. He may know where the investigators can find more information. For a price.

'The Hanged Ghost:
Ghosts of past executions may know of Tower lore possibly even location. Names of the (legally) executed are kept in the church records.

Gypsies: 
Ghosts, sightings, the Hanged Ghost.
Location of the priest's hidden grave (the silver key). This will be a VERY costly secret.