Even for the likes of Joan Didion, Vanessa Redgrave, and David Hare, the prospect of creating a devastating—yet somehow wry—one-woman show about a writer’s descent into unbearable grief was rather daunting. In 2005, The Year of Magical Thinking, Didion’s account of the twelve months of mourning and temporary madness that followed the sudden death of her husband, John Gregory Dunne, became the then-70-year-old’s best-selling book, winning a National Book Award. Shortly after Didion finished it, her daughter, Quintana, whose serious illness coincides with Dunne’s death in the book, also died. Didion could have revised her work, but instead she took on an even greater challenge. She allowed producer Scott Rudin to talk her into adapting the story as her first-ever play. From the outset, says Didion, “it seemed perfectly clear to me that I couldn’t do it without incorporating [Quintana’s death]. It didn’t seem difficult technically; it was somewhat difficult emotionally, naturally. But I had to go through it anyway.” Didion and Hare, the British playwright (Stuff Happens, The Vertical Hour) who would serve as director, also quickly decided that Vanessa Redgrave, and only Vanessa Redgrave, was right for the role—that of a character named Joan Didion. Together these three—what Redgrave calls the “troika”—have spent countless hours refining the words, pauses, and gestures that make up this production. It was an unusually fluid exchange among equals: Hare would act out bits of a scene; Didion would suggest the character’s reactions; Redgrave even got a few lines changed. Luckily, Hare and Redgrave both share Didion’s obsessive attention to detail, along with her habit of revising right up until publication (or, in this case, opening night, which arrives March 29). But “once a play goes into rehearsal it’s like a freight train,” Didion says. “It’s very hard to change the track without derailing it.” What exactly happens, though, on the way into the station? During the play’s first week of previews, we followed the three principals for a day as they went through makeup in the dressing room, text revisions, rehearsal, an evening performance, and the quick dash home after curtain call—where they’d get ready to do it all over again.