Harry Potter and the Philosopher's Stone, the first book of JK Rowling's novels about a child wizard, was released in hardcover in 1997 and found in a Highland bookshop's bargain bucket and may be worth£60,000.
Hansons Auctioneers says it was one of 200 copies issued to retailers from the book's first print run, with a suggested retail price of £10.
A Scottish woman, who has not been identified, discovered the book on a family caravan holiday in Wester Ross in the late 1990s, shortly before Rowling's books became a global success.
Hansons expects the copy to fetch between £40,000 and £60,000 at auction on December 11th.
The book was purchased by the vendor, a 58-year-old retired manager, at a bookstore café at the end of a single-track road in Ullapool.
She identified the author's name after reading an interview with Rowling in The Scotsman.
She said: "The bookseller had placed it in a wicker ‘bargain bucket’ basket on the floor."
"Because it had no dust jacket, I got a couple of pounds knocked off the price."
"Our two children enjoyed the wizard tale as a bedtime story all through that holiday in 1997.”
The retired manager has stored the book in a cabinet beneath the stairs at her house since purchasing it.
In Philosopher's Stone, Harry Potter sleeps in a closet beneath the stairs at his home.
Hansons said the hardback was one of the rarest and most prized Potter books and the "holy grail" for collectors.
Harry Potter books expert Jim Spencer said: “These first issues are getting harder and harder to find."
"This must be one of the few remaining copies that’s been in private hands since it was purchased in 1997."
“It’s a genuine, honest copy - and a fantastically well-preserved example."
The Harry Potter books are among the best-selling books of all time, with over 600 million copies sold worldwide.
They were adapted into films starring Daniel Radcliffe as Harry Potter, and a TV series is in the works.