Michael Douglas has confirmed a romantic relationship with a famous co-star that the pair publicly denied for four decades, revealing the truth in his new memoir, One Helluva Ride.

Who it was with

The relationship was with Kathleen Turner, his co-star in the 1984 film Romancing the Stone. According to an excerpt published by PEOPLE, Douglas wrote that he was immediately drawn to Turner when they first met to discuss her taking the role, describing her as "smart, funny, and sexy with a deep, sultry voice that became her signature," adding: "I instantly liked her, and we were immediately attracted to each other." At the time, Douglas was separated from his first wife, Diandra Douglas, though the pair remained legally married and shared a young son, Cameron.

How the relationship began and was kept secret

Douglas wrote that their on-screen chemistry led many to assume they were together during filming, something both consistently denied through Romancing the Stone, its sequel Jewel of the Nile, War of the Roses, and even years later during press for The Kominsky Method. He admitted: "The official story went as follows: Yes, we confessed, we had amazing chemistry. Yes, we were both, as Kathleen said, 'terrible flirts', and yes, we were both tempted, but nothing ever happened between us. That was a lie." He said even director Robert Zemeckis and co-star Danny DeVito were unaware, and that he would visit Turner's hotel room after filming once everyone else had gone to bed.

He wrote: "The truth is that during the production of Romancing the Stone, Kathleen and I fell hard for each other and began a relationship. It wasn't a fly-by-night affair; it grew naturally from how closely we were working together, how much pressure we were under, how much we respected and cared for one another, and how attracted we were to each other. Like every other guy in the world at the time, I was knocked sideways by Kathleen."

How it ended

According to Douglas, the relationship ended after Diandra travelled to Mexico with their son and grew suspicious, later speaking privately with Turner to make clear she still considered herself married to Douglas. He wrote: "A woman's intuition, I suppose. At some point, she was alone with Kathleen and made it clear to her that we were still married. Her view of the terms of our separation was different from mine. This gave Kathleen pause." He said Turner didn't want to interfere, and the relationship ended, with Douglas returning to Diandra for their son's sake, though he writes in the memoir that the reconciliation shouldn't have happened.

Their relationship today

Despite their past, Douglas and Turner have remained close friends, and he says he asked her permission before including the relationship in his memoir. Douglas has been married to Catherine Zeta-Jones since 2000, with whom he shares two children, following his divorce from Diandra in 1995.