During the excavation, you found an old document on the site. It described a treasure, hidden by templar knights. You couldn't fully get the exact location, just roughly. You kept it as a secret because you didn't want to share with anybody, nor you wanted to give it to the museum. This should be it. Everything is here. The mill, the lake, the cottage. There are a lot of hidden signs and hints, left by the templars. They marked the place to know where is the treasure. The document didn't describe the encoding, so you'll have to figure it out on your own. Good luck!
June 10, 2015