Charles Rex Arbogast/Associated Press

Terry Dulin had one of the most colorful and grandiose collections of rare Kris Bryant prospect cards on the planet. A full-time food broker who deals baseball cards on the side, Dulin stood to gain quite a bit of side money by showcasing the collection at the 2015 Fanatics Authentic Sports Spectacular—one of the largest baseball card shows in America.

But during the convention, another unnamed collector introduced Dulin to a card that begged to be added to his already sizable collection: a 2013 Bowman Chrome Kris Bryant Black Wave autograph card. Dulin had never seen or heard of this card before and was a bit skeptical of the owner when he saw it.

"I even asked him, 'Are you sure this thing isn't backdoored?'" Dulin recalls of the encounter, referring to the practice where an employee unlawfully takes their company's property. "And he said, 'What does backdoored mean?' And I was like, 'Well, they come from the factory because these cards are not in existence. If anyone had seen a Kris Bryant card, I would have known about it. And I have never seen the card.'"

Photo courtesy of Jesse Koontz

Photo courtesy of Jesse Koontz

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After a little deliberation, Dulin eventually bought the card at the show for $850—a steal compared to its current value. He eventually sold the card a few months later to another collector for $1,100. According to Dulin, this collector had never seen the card either.

The two weren't alone, as it turns out, because nobody had ever seen it. In fact, this card may be the only copy confirmed on the resale market despite the fact that its print run is numbered to 50.

The 2013 Kris Bryant Black Wave, along with the Blue Wave variation of this card (Bowman issues several colored "refractor cards," each numbered to a specific production limit), appears to have never been found in a pack or surfaced online—this card the sole known exception.

If there are supposed to be 50 copies of each card—where are the other 49?

This type of mystery is not typical of cards with comparable print runs, according to Jesse Koontz, the card's current owner and Kris Bryant card supercollector. Koontz says he purchased this Black Wave in early 2016 for about $8,000, and his Bryant collection (pictured below) is worth about $80,000 in his estimation.

Photo courtesy of Jesse Koontz

"Typically with a card numbered to 50, you'll see at least one or two copies on eBay at all times," Koontz says. "I had never seen one."

There was one other unconfirmed sighting of the card: Baseball card dealer Colin Masters says he almost bought one at a card show in Albany, New York, a few years ago, but he passed up on the chance because of some minor damage on the bottom right-hand corner of the card. The collector allegedly wanted about $900 for the card, a price Masters now says he wished he paid: "Looking back on it now, I probably should have just bought it for the rarity of it."

It's not clear, however, if this is the same card Koontz currently has.

The strange circumstances around the card do not stop with its Bigfoot-like rare sightings. On September 3, 2014, according to a card "population report" by Beckett—a card grading and autograph authentication company—15 versions of the Black Wave, along with 15 versions of the Blue Wave, were graded in immediate succession in a bulk submission. This bulk submission and the fact they were graded sequentially probably means one person had all of the cards graded at the same time.

Koontz's card was graded on October 7, 2015, per the population report, making it the only version of this card in the report that was not part of the September 2014 submission.

Aside from the one card Koontz owns, the population report is the only documented evidence that the card even exists. It doesn't even appear to be listed on Beckett's baseball card price guide—long considered a bible of sorts for collectors.

Charles Rex Arbogast/Associated Press

The Bowman Chrome prospect cards, like the ones Bryant has, are typically considered by collectors to be a player's "true rookie card." Cards with autographs are even more valuable, for obvious reasons. So if there is one person with nearly all of these Kris Bryant cards, the collection could be valued over $500,000.

Beckett does not divulge information on customers who have cards graded, so there's no telling who may have done this or what their motives were. But the bulk grading submission raises many questions. How would somebody have 30 copies of two cards that most collectors don't even know exists?

Moreover, even if there's a fair explanation for the bulk copies—where are the rest?

Koontz is as perplexed as anyone: "The Black Wave and Blue Wave, there's 50 of each. Fifteen were graded, but they never released that remaining 35. And so that's kind of where the question comes: We know they're autographed by Kris Bryant, but why didn't they issue them?"

Topps did not respond to several requests for comment on this story.

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Could this all be the product of a manufacturing error? Masters has opened many high-end packs and boxes as part of his baseball card hobby for years, and he says while this kind of an error is not common, it's something he has seen in the past.

"[It] could be that there was a manufacturing mistake. They very well could be bunched together in a pack," Masters says. "Theoretically, it could happen. I've seen it happen. I've opened up packs and had six of the same guy or multiple autographs. It very well could happen like that."

Guesses and theories are all collectors have at this point.

As for the one Black Wave that we know exists, Koontz says it is not for sale—but every man has a price.

"Right now, I probably wouldn't entertain any value less than $20,000," Koontz says, in a hypothetical scenario of selling the card. "Money can always be made, but things like that are hard to come by. I like having the asset itself because, in my mind, it's just going to go up in value."