'Antiques Roadshow:' See the great story behind a rare Rolex

If you thought your standard Rolex watch was expensive, Monday night's episode of "Antiques Roadshow" will have you thinking twice about that.

Behold: A rare 1940s Rolex military watch with an estimated value and an incredible backstory you won't believe.

"I feel this will sell very easily at auction between $40,000 to $50,000," said appraiser Jeff Cohen on "Antiques Roadshow."

"Oh, my gosh," said the watch's owner.

"Don't fall out of the chair on me now," said Cohen.

We were just as shocked as the watch's owner there when we heard that whopping price tag!

And "Roadshow" fans on Twitter definitely agreed, with one user claiming it's pieces like this that make the show so great.

But just wait -- the story behind this rare Rolex is even more surprising.

It originally belonged to the owner's late stepfather, Jerry Sage, who was a POW in Germany during WWII.

He had been working behind enemy lines in North Africa to delay the Nazis' arrival when he was captured and put in a prison camp along with several other Americans.

But he managed to escape several times and aided British officers in staging the now famous "Great Escape."

"It is the sworn duty of all officers to try to escape."

And if that true tale sounds familiar, that's probably because it was later turned into a book and then into an iconic movie of the same name.

Of course, that incredible backstory was a big part of what made Sage's Rolex so valuable.

But, fortunately for his stepdaughter, the watch also has an original black dial, which is extremely rare and added even more value to it.

The owner probably said it best when she first learned how much her timeless timepiece is worth...

"Mercy!" said the owner.

Mercy, indeed!

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