Roy Langbord had guessed that someone in his family might have hidden away a great treasure decades before, but not until his mother had him check a long-neglected safe-deposit box did he realize just how great it was.

Inside the box, opened in 2003, he found an incredibly rare coin, wrapped in a delicate paper sleeve. It was a gold $20 piece with Lady Liberty on one side, a bald eagle flying across the other and, at Liberty’s left, the four digits that made it so valuable: 1933.

The famous “double eagles” from that year were never officially released by the government. Only a few had ever made their way out of federal vaults, and only one had ever been sold publicly, in 2002. The price: $7.6 million.

And there were nine more of them in the safe-deposit box.

But after the Langbord family took the coins to the United States Mint to be authenticated in 2004, they got a rude surprise. The Mint said the coins were genuine and kept them.