(Sept. 14) -- Superman is faster than a speeding bullet, more powerful than a locomotive and able to leap tall buildings in a single bound, but who knew that he had an even greater power: being able to stop bank foreclosures.

Yep, he's doing that too. Well, at least one of his comic books is.

Oh, but what a comic it is: It's a vintage copy of Action Comics, No. 1, dating from 1939, that represents the Man of Steel's very first appearance and the debut of the superhero genre in general.

"This is the Holy Grail of comic books," said Stephen Fishler, the co-owner of ComicConnect.com and Metropolis Collectibles, the world's largest vintage comic book dealer. "Until recently, only about 99 were known to exist, and most of those were in the hands of collectors."

Things changed two months ago, when a couple contacted Fishler and his partner, Vincent Zurzolo, wanting to discuss an old comic they had found in their attic. That old comic turned out to be a copy of Action Comics that was eventually rated to be "Very Good-Fine" by experts.

"The couple were going through a foreclosure and were actually going through some boxes in the attic to get things ready before the bank took over the house," Fishler told AOL News. "There were about 50 boxes total. There was an old movie magazine and four other comic books from the late 1930s that didn't have much value."

Fishler said the couple have asked him to keep their identities and address secret.

"I can only say that they live 'down south,'" he said. "The house has been in the family a long time, and I think they want to keep this a secret from other relatives who might make a claim on the book, and also because it's embarrassing to admit you're at risk of losing a house.

"Basically, they had taken out a second mortgage to finance a business that didn't work and they found this comic at the last minute."

Although the couple weren't big comic book fans, they knew enough to recognize that Action Comics No. 1 might have value and did some research before finding Fishler and Zurzolo.

"We've had success selling other copies of Action 1, including one for $1.5 million," Fishler said. "That one rated 8.5, whereas this one is around a 5, still in good shape, but worth more than $380,000."

However, Fishler believes the so-called "Foreclosure Comic" could get even more when the auction for the book ends Sept. 20.

But even though the couple's money problems seemed solved when they found the book, it wasn't that simple, he said.

"I had to talk with a gentleman from a bank and explain the value of the book and when the auction would take place," Fishler said. "He was relatively suspicious at first."

That banker wasn't the only one. Fishler admits the couple initially had a hard time enjoying their sudden bout with good fortune.

"What's bizarre with these people is that most folks who found something like this in their attic would be happy," Fishler said with a laugh. "We met in a strip mall restaurant and they were nervous about touching the book and traveling with it. They told me they had it in their car trunk and went out to get it and there it was. I said, 'Yep, it looks like it did on the scanned picture you sent me.'

"They wanted to take it back to the trunk and I had to point out it was probably safer with them than in a strip mall parking lot. I've also had to explain to them that they should be happy. I told them that I'd love to be in their situation but they were, at first, fixated that it wouldn't pan out."

Apparently, Fishler is as good at understanding the human psyche as he is at pricing comic books.

"As the auction date grows closer, the couple is now allowing themselves to enjoy the experience," he said.