The Three Investigators and the Silver Mine

Isn't it strange that the wealthy real estate agent bought the old, abandoned silver mine, the notorious "Death Trap"? But that's no reason to prematurely suspect him, because many other strange characters are suddenly appearing. Who, for example, is the unknown person who is messing around in the barn at night and obviously looking for something? And the rock that Justus finds, doesn't it have a golden trace? Mystery after mystery. But then the three ??? make a gruesome discovery in the old mine ...

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