NEW YORK (AP) — Two of Robert Ludlum’s blockbuster creations, the maverick-spy Jason Bourne and the top secret Treadstone program, will soon be at work again

Putnam announced Wednesday that it had a four-book deal with the late author’s estate for two thrillers each in the Bourne and Treadstone series. “Robert Ludlum’s The Treadstone Resurrection,” written by Joshua Hood, comes out Sept. 17. “Robert Ludlum’s The Bourne Conspiracy,” by Brian Freeman, is scheduled for next year. Details on the other two books were not immediately available.

Ludlum, who died in 2001, sold hundreds of millions of books with such best-sellers as “The Bourne Identity” and “The Bourne Supremacy,” both of which became films starring Matt Damon. In 2004, St. Martin’s Press continued the Bourne novels with “The Bourne Legacy,” by Eric Van Lustbader.