Dan Brown, author of "The Da Vinci Code," returns with "The Secret of Secrets"

The wait has lasted eight years. The new esoteric thriller by American Dan Brown, author of The Da Vinci Code phenomenon, is out this Tuesday, September 9. It has been translated into 16 languages ​​and is being published simultaneously across the world, with a print run of 1.5 million copies in the United States and 500,000 in France, according to its publisher.

The Secret of Secrets , which has nearly 700 pages in English and 640 in French, marks Dan Brown's return eight years after the publication of his last novel, "Origin."

This is the sixth volume in the adventures of the hero Robert Langdon, a specialist in esoteric symbols. They take place in Prague, around an "explosive essay on the nature of human consciousness that could overturn centuries of established beliefs," according to French publisher JC Lattès.

Dan Brown called The Secret of Secrets "by far" his "most complex and ambitious - and also his most entertaining - novel." "We're expecting excellent word of mouth," JC Lattès CEO Véronique Cardi told AFP, because the book "mixes car chases, reflections on neuroscience, and Scandinavian mythology."

The initial print run of 500,000 copies represents the largest of the year for the French edition, according to her.

For this simultaneous release in the United States, the United Kingdom, Germany and Italy in particular, a "commando operation" was carried out to quickly translate and print the book while avoiding any leaks, explained Véronique Cardi.

The two French translators worked offline and in a secure location, while the three printers were subject to "extremely strict confidentiality clauses."

Dan Brown, 61, begins a month-long promotional campaign in New York on Tuesday that will take him to 12 countries. He will meet with readers in Paris on October 1 at a meeting organized by Fnac.

After two relatively unnoticed first books, the American author, a discreet high school teacher, signed one of the biggest bestsellers in world history in 2003 with "The Da Vinci Code".

With a complex plot revolving around the supposed descendants of Jesus, the Mona Lisa and Freemasonry, the novelist had attracted the admiration of millions of fans, but also the criticism of scholars for whom his novels are riddled with errors and nonsense.