Lost in the Dark Game

The other day Julia and Dylan received an invitation to visit from an old friend. They had not seen each other for many years and were delighted to set off. As soon as the boys arrived at the place where their friend's mansion locates, they were shocked. The building seemed long since abandoned, and there was no trace of human habitation here. It was oppressive and depressing as if every corner was haunted. The boys hired a detective to get to the bottom of this strange story. Guess who that detective would be? You, of course!