The Lost Treasure Map

The treasure is buried away for centuries, hidden away in a secret chamber, with no precise suggestion of its existence, even after being scanned by archeologists with the most advanced and up-to-date equipment!
The only clues to its whereabouts are an ancient riddle: where the last dwell, the markings on a tomb, and legends of treasure passed down by generations of castle owners.
The castle's mysteries are lost in time, for someone, someday, to come along and find the answer to, to discover what is hidden there.
A group of people are forced into staying at the castle, for a week, to explore the immense castle and vast estate as they are fanatical with hunting and getting their hands on the treasure, which they believe has been left there by the late owner, even after two major murders and televised police investigations.
The treasure is found where nobody anticipates it to be and they guess where the killer will strike and catch him, and are amazed at his identity!