The books are piled high and scattered randomly, as they have been for 30 years.
In the past, bookseller Noel Brookes could direct each customer to the book they wanted with barely a pause for thought.
Now though, the doors are locked, Mr Brookes has not been seen and the abandoned books are being farmed out to other second-hand stores.
Landlord Nigel Collins has not heard from Mr Brookes for three months, nor received rent for the property in Queens Road, Brighton.
All attempts to contact him have failed.
Mr Collins has been forced to shut the shop and has started selling the books to shops in central London.
Fellow shopkeepers in Queens Road are baffled by the sudden disappearance of a man they regularly saw but never really knew.
Pam Page, of Flip 'N' Funki crafts shop, said: "He was a bit of an eccentric and kept himself to himself.
"The shop was chaotic. It's tidy now compared to how it was."
Michael O'Maoileoin, of Haywards Heath, was a regular browser for 20 years.
He said: "There was no method or system at all.
I used to wonder to God how he ever did any business.
"But if you're a browser, it was a pleasure to explore. You never knew what you'd come out with."
Among Mr O'Maoileoin's treasured purchases from the store was a 1938 two-volume James Joyce, which has the inscription: "Not for circulation in the British Isles."
Despite his regular visits, Mr O'Maoileoin was never able to enter into conversation with the taciturn, cigarette-smoking shopkeeper.
He said: "The best you could hope for was a gruff 'What?' when you asked him something. Him saying the price was the end of the conversation.
"I never found out anything about him. All you got was him eternally standing there like a statue.
"But he must have had an amazing memory because he could tell you approximately where every book was. He never went to get it for you."
Mr Brookes refused to accept credit cards or cheques, taking only cash, and had no computers to help him with his filing or accounting.
He used a property opposite the shop to store more books.
Mr Collins, who is based in central London, said: "I've been trying to get in touch with Mr Brookes. He owes me rent. He just left.
"I've heard he's been seen a couple of times but I haven't had any response when I've tried to contact him.
"If he wants the books, he can have the ones that are left. I wish him well but the shop can't just sit there forever."
New tenants are living at Mr Brookes's last known address in Lansdowne Road, Hove.
They have been there for five weeks and said they knew nothing about him or his whereabouts.