Rick Whitelock received a mysterious phone call from a blocked number on Monday.

The man on the other end wouldn't reveal his name or location, but claimed to have something Whitelock said he's been sick over for days: a box of missing comic books valued at what he estimates is $85,000.

Whitelock, owner of New Force Comics in Panama City, reported the box missing to Tampa police on Saturday at Tampa Bay Comic Con, where he'd been a vendor. He said the man described books that hadn't been mentioned in news reports.

He said the man told him he wasn't sure how he'd ended up with the box containing such rarities as Amazing Fantasy No. 15, Uncanny X-Men No. 1 and Incredible Hulk No. 1, but realized the mistake while later unloading his own boxes after the convention. Whitelock told police the man said it was possible he or a helper had picked up the wrong box.

Related: 'Amazing Spider-Man' No. 1 among $85K in rare comic books missing at Tampa Comic Con

"He saw my sticker that says New Force Comics so he Googled us," Whitelock said "He freaked out when he did, because he saw all these news stories talking about stolen comic books."

Whitelock wanted to drive to pick up the comics immediately, but the man refused. He asked the man to drop the books off at a friend's comic book shop in Tampa. The man refused again.

"He wants to remain totally anonymous, which, as long as this ends with me getting my comics back, I'm totally fine with that. But until those books are in my possession, I won't feel better. … I haven't slept in three days. I've lost seven pounds. I just want some peace."

As of Tuesday afternoon, Whitelock was waiting for the man to call him back with a Fedex tracking number, which is how he'd agreed to return the missing merchandise.

Whitelock arrived at the Tampa Convention Center on Thursday with more than 180 boxes of comic books. He stacked them in a staging area among the other vendors' boxes, where they sat for several hours as he went back and forth to his van, he said. He moved them again that night, to his booth on the main floor, but realized Friday morning a box of around two dozen Silver-Age comic books was gone.

"There would have been periods of time when a box would have been out of sight for a few minutes, but that's the way it goes," Whitelock said. "You have to leave your booth and go back to the van, and everyone's doing the same thing. It has worked fine for years. You have trust."

Whitelock said after the story appeared in the Tampa Bay Times, then spread to national comic book blogs and the Comic Books section on Reddit, he'd received dozens of calls from people in the comic book community offering their help and support.

The story may have gained attention due to the rarity of the missing books. The box contained two copies of Amazing Fantasy No. 15, the first appearance of Spider-Man. Those copies, CGC graded at 5.0 and 4.0 out of 10 by Certified Guaranty Co., which grades comic books based on their condition, were priced at $19,995 and $15,995 respectively. The box also contained a copy of Brave and the Bold No. 28, featuring the first appearance of the Justice League team, which Whitelock had priced at $15,000.