Pakistan, Oct. 4 -- Michael Douglas is releasing a decades-long secret. Over 40 years after he and Kathleen Turner praised eyebrows with their onscreen chemistry in the 1984 film Romancing the Stone, Douglas-who was separated but still legally married to Diandra Luker at the time-admitted that he and his costar did engage in an affair after denying it for years.

Douglas, who has been married to Catherine Zeta-Jones since 2000, describes meeting Turner in his new memoir One Helluva Ride, detailing their mutual immediate attraction.

"The chemistry I had with Kathleen Turner was so strong, audiences have been certain for years that we were in a relationship together while making the film," he writes in the book, out Oct 6, according to an ...