A book about double killers Colin Howell and Hazel Stewart, which was serialised in the Belfast Telegraph, has sold out shortly after going on sale.
Let This Be Our Secret is being reprinted just days after it was launched in Belfast.
Publishers Gill & Macmillan confirmed it is the fastest selling book in Northern Ireland and went straight to the top of the Top 10 bestsellers list.
Eugene McAlinden, store manager of Easons in Donegall Place, Belfast, which sold out after 300 remaining first issue copies were bought inside 24 hours, said: "The demand has been phenomenal. We knew it would sell, but not this quick. It has surpassed all our expectations."
The book, about the sensational north coast killings, was written by journalist Deric Henderson.
He said: "There has been a quite extraordinary reaction to an extraordinary story and the interest in the Irish Republic has been huge as well."