Maureen Callahan's new book exposing Kennedy family scandals is an instant New York Times bestseller... beating Dr. Fauci's memoir in prestigious ranking!

DailyMail.com columnist and author Maureen Callahan's bombshell new biography of the Kennedy family has become an instant New York Times best seller. 

'Ask Not: The Kennedys and the Women They Destroyed' was published on July 2 and debuted last week in the No.2 position on the Times's prestigious book-sales ranking.

Callahan's biography beat other popular new books to the top spot, including Former Chief Medical Advisor to the President Anthony Fauci's memoir, which dropped down to the No.4 position on the 'Combined Print & E-Book Nonfiction' list.

In the UK, meanwhile, 'Ask Not' took the No.1 position on the Sunday Times's best-seller list this weekend. 

These successes come after it debuted in the No.1 spot on several other sales charts, including Amazon's rankings, within hours of being published earlier this month.

As well as claiming the top position in Amazon's 'Women in History' section, it was also first among 'Women's biographies'.

In fact, such was the demand for the book, Amazon temporarily sold out of copies.

Callahan has received rave reviews, including from podcaster Megyn Kelly, who described the biography as 'the must-read book of the summer.' 

'There's so many interesting new nuggets on this bizarre family. Trust me, you're going to want to read it and buy it for everyone you know,' Kelly said.

A similarly glowing review in The Guardian praised the book as an 'eye-opening exposé', while Town & Country magazine described it as 'a searing, no holds barred account of scandal'.

Last month, the Mail published four exclusive extracts of the book.

These included shocking new revelations such as: untold details of JFK's 1963 assassination; his wife Jackie's second marriage to Aristotle Onassis and the 170-clause prenup they negotiated; unearthed claims that could implicate 'lady-killer' Kennedys in the death of Marilyn Monroe; and a stunning new theory about the 1999 plane crash that killed JFK Jr. and Carolyn Bessette.

Callahan's previous book, 'American Predator' – about the serial-killer Israel Keyes – was also a New York Times best-seller.