Dan Brown's next thriller, 'The Secret of Secrets,' to be published Sept. 9

NEW YORK — Dan Brown' s next global, multi-tiered thriller finds protagonist Robert Langdon journeying from Prague to New York to London as he evades a would-be assassin and ponders the depths of human consciousness.

Doubleday announced Wednesday that ''The Secret of Secrets," his first Langdon novel since ''Origin'' came out in 2017, will be published Sept. 9. Brown, best known for the blockbuster ''The Da Vinci Code,'' is calling it his ''most intricately plotted and ambitious novel.''

''Writing it has been an unforgettable journey of discovery,'' he said in a statement.

Brown's new novel begins with Langdon, the Harvard symbologist, in Prague. According to Doubleday, he plans to see a lecture by noetic scientist and emerging love interest Katherine Solomon, only to have her talk become a murder scene and for Solomon to disappear.

''As the plot expands into London and New York, Langdon desperately searches for Katherine . . . and for answers,'' Doubleday announced. ''In a thrilling race through the dual worlds of futuristic science and mystical lore, he uncovers a shocking truth about a secret project that will forever change the way we think about the human mind.''

Brown has set previous books in France, Italy and Spain among other countries and researches his locations in person. He said in a statement that his fascination with Prague "began with its deep history of mysticism and the occult. It is a labyrinth of enigmatic sites — an ideal backdrop for a Robert Langdon thriller –- a city of secrets, both ancient and modern.''

Brown added that ''The Secret of Secrets'' was also a chance to indulge another longtime obsession — the mind itself.

''I happen to believe we are on the cusp of a major revolution in the way we think about our brains and our relationships to each other,'' he said. ''Cutting-edge science is now exploring advanced models of consciousness that seem poised to explain some of the mind's deepest mysteries. I chose this topic because I find it irresistibly compelling, and also because it is relevant to every single one of us.''

Doubleday plans to release the book in at least a dozen countries, including Czech Republic, Turkey, Spain and Finland. Brown's other novels include ''Angels & Demons,'' ''The Lost Symbol'' and ''Inferno.''