Hannah Murray, the British actress best known for her role as Gilly on the hit HBO series "Game of Thrones," has detailed a harrowing experience involving an alleged wellness cult that resulted in a severe psychotic episode and an involuntary stay in a psychiatric hospital. The 36-year-old actress opens up about this dark chapter in her life in her upcoming memoir, "The Make Believe: A Memoir of Magic and Madness," with excerpts and interviews bringing the shocking story to light .

The actress, who also rose to fame as Cassie on the British teen drama "Skins," said her journey into the group was a gradual one. According to Murray, her introduction came through a personal trainer on the set of the 2017 film "Detroit," who recommended an "energy healer" named Grace. In the midst of a deep depression and struggling with the emotional toll of filming intense scenes, Murray was desperate for help .

This initial search for wellness and healing led her deeper into a structured organization run by a charismatic leader she refers to only as "Steve." Murray describes the group as having a pyramid structure designed to exploit members . What began as simple wellness guidance evolved into expensive and controlling classes. She admitted to spending thousands of dollars in pursuit of "wisdom and specialness," a path she now acknowledges was manipulative .

The situation reached a crisis point just hours before her initiation ceremony into the group. Murray described a terrifying psychological breakdown while in London. She recalls locking herself in a bathroom, enduring excruciating pain that felt like "giving birth through my skull," while members of the cult reportedly gathered outside, chanting, "Be gone, evil spirit in Hannah" . She began to experience intense hallucinations and delusions, including hearing Steve's voice in her head and believing he was her "King" and "God" .

The situation escalated so severely that emergency services were called. Murray was pinned down by a group of men and rushed to Gordon Hospital in London, where she was detained for 28 days under the Mental Health Act . During this time, she was officially diagnosed with bipolar disorder, a condition that provided clarity regarding her mental state .

In excerpts from her memoir shared with The Cut, Murray writes about the manipulative nature of the group leader, Steve. She reveals that he allegedly told her she "had been possessed by a demon" and even claimed to have "performed an exorcism" on her while she was filming "Detroit" in 2017 . Even from her hospital bed, her texts to him fluctuated wildly, accusing him of being an "evil cult leader" one moment and expressing gratitude the next. Despite her accusations, Murray writes that Steve denied all wrongdoing .

Murray admits to being completely brainwashed. "I had been completely taken in by everything he said," she writes. "I believed him. I believed he was not a cult leader. I believed everything he told me" . After leaving the hospital, she acknowledges that she was not cured, stating she entered "extremely psychotic and left somewhat less so" . Reflecting on the experience, Murray hopes her story can help others understand the dangers of such groups. "It's easy to go, 'Well, that would never happen to me,' but we do ourselves a disservice when we start saying that, because you don't know," she told The Guardian .

Her memoir, "The Make Believe: A Memoir of Magic and Madness," is set to be released on July 11, offering a complete look at her experiences and recovery .