Watching the charismatic actor, Alan Cumming, on the CBS television show, The Good Wife, or PBS’s Masterpiece Mystery, seeing him in films or on the stage, where he’s currently getting raves on Broadway as the emcee in Cabaret, you’d be looking at the picture of success. But as Cumming reveals in his memoir, Not My Father’s Son (HarperCollins, Oct.), there’s more beneath the surface than you might surmise. “I think people will be surprised by the sheer insanity of the events in my life and by the bleakness of my childhood in Scotland,” he says, adding, “and also how my mom, my brother, and I came out of this horrible situation. It’s a miracle that we’re all so happy and well-balanced.”

Cumming was prompted to reveal his personal story because of what occurred in the summer of 2010. He’d been asked to appear on a U.K. genealogy show, Who Do You Think You Are, hoping to find out the truth behind the mysterious death of his maternal grandfather. Coincidentally, the night before filming started, his older brother came to him with a message from his father, whom he hadn’t seen in 16 years. “He told me he was not my real father, and I was emotionally derailed. But my father was a horrible man—I wanted not to be his son. It was a difficult thing to deal with, so writing the book was a good way to try and make sense of it all.”

The actor is hesitant to talk about the specific traumas of his childhood, but he admits that he and his brother and mother were victims of their father’s physical and emotional abuse. How he survived is eye-opening. “In writing this book I realized how much my acting originated from dealing with my father—having to sense what mood he was in, being able to react quickly and hide things. Abuse victims have to be so quick on their feet and have a kind of radar to work out how they need to react, and figure out how the abuser is behaving. I had to learn very fast traits that are tricks that an actor uses. It wasn’t a very pleasant thing to realize that the origins of my acting came from such a horrible source, but maybe I wouldn’t have been an actor if I hadn’t had the childhood I’d had.”

Although he went through so many rough patches, Cumming hopes his story sets a positive example. “There’s abuse of all kinds everywhere, and I think it’s great to hear stories and see that people can come through it, especially someone like me that people know and think of as a successful person,” he says. “There’s a kind of a vindication at the end of my book—my mother, my brother, and I come through all of this and triumph in that we are a stronger family then we ever were.”

Thanks to his schedule in The Good Wife, which requires him to be in New York City for roughly nine months of the year, he was able to write his book in the Writer’s Room on Broadway and Astor Place. “I had a lot of time when I could be writing. I was so excited to find this room where everyone is just writing; there’s a roomful of people doing exactly the same as you. No one is allowed to talk and everyone is very respectful. I liked the camaraderie of it.”

Cumming is signing galleys of his memoir today at the ticketed signing in the Autograph Area at Table 3, 1–2 p.m., and is the emcee for Saturday morning’s Adult Book and Author Breakfast, sharing the podium with Martin Short, Lena Dunham, and Colm Toíbín.