When a Minnesota home remodeler decided to plunk down $10,100 for a fixer-upper to rehab, he just assumed it was a no-lose investment. Little did he know about the rare comic book he’d find stashed in the wall of the house.

While gutting the house one day, he stumbled upon an Action Comics #1 from 1938, which just happens to be the book that introduced a red-caped hero known as Superman.

“The most important comic book in the history of comic books,” writes ComicConnect, the online auction site where the Minnesota man’s find is now up for bid.

“I knew it was worth money,” the man tells the Minneapolis Star-Tribune. “But I had no idea how much.”

Right now, the highest bid is more than $107,000. The value of the found comic book would probably have been even higher if the homeowner’s grabby in-laws hadn’t gotten their hands on it.

“They got all excited and tried to take it,” he says about the incident that resulted in a tear of the back cover. “I understand it’s something cool, but told them: ‘You don’t have to act so rude. I brought you in to show you, don’t grab it.’”

“That was a $75,000 tear,” the co-owner of ComicConnect explains to the Star-Tribune.

The auction continues until June 11. In the end, the homeowner will end up getting half of whatever the highest bid ends up being. Right now, that would still be more than five times what he paid for the house.