The tale by Serbian author Mirjana Djurdjevic imagined the former Bosnian Serb leader, 63 - a trained psychiatrist - was working "in plain view" in a clinic in the capital.
According to The Sun, Djurjevic wrote of Karadzic using a wacky haircut and eccentric white hat and black suit to deflect attention from his "cold" eyes.
The real Karadzic - arrested in Belgrade last week for the massacre of 20,000 civilians in the 1992-95 civil war - wore black clothes and a hat, and had a bizarre dyed topknot.
He is said to have abandoned a move to Russia in 2006 - at the time book First, Second And The Third Man came out.
Mirjana said: "There are so many weird similarities. All I did was use my imagination."