Mystery of the Missing Map by Lois Walfrid Johnson

In the dark of night Kate, Anders, and Erik travel to Michigan to meet Cousin Megan. As the train clickety-clacks into Copper Country, Kate overhears a whispered conversation about an easy steal, the man who owns the mansion where Megan's father is caretaker, and a plan involving Anders and Erik. When Kate sees her cousin for the first time they're like identical twins except for one thing--Megan is blind. As two people lurk in the darkness near the mansion, danger trails the four friends. Can they find the long-lost treasure map in time? Act with courage in spite of fear? Stay ahead of the thieves who also search for silver nuggets from Central Mine? And when rocks fall deep within a copper mine, what becomes the biggest treasure of all?

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