Scott Eyman’s new biography “Charlie Chaplin vs. America” (Simon & Schuster, publishes Oct. 31) chronicles the amazing – and still shocking – fall from grace that led Hollywood’s first global superstar to virtually disappear into a voluntary Swiss exile.

As WWI raged Chaplin’s Tramp made him famous in every country of the world and wildly wealthy. Yet as post-WWII America went through political convulsions with anti-Communist conspiracies and purges born out of moral indignation, Chaplin in the late 1940s became a target of the FBI chief J. Edgar Hoover’s obsession with his sexual life and his liberal politics.

But Eyman, the best-selling biographer of John Wayne and Cary Grant, doesn’t confine himself to just that chapter of Chaplin’s extraordinary life.

“My intent was to narrow it to 12 years,” Eyman. 72, said in a phone interview. “Then I thought, I can’t assume 21st century readers know anything about Charlie Chaplin, about his childhood and all that. And if you don’t understand about his childhood, you don’t understand about his career. If you don’t understand about his career, you don’t understand about what happened in the ‘40s. So I had to introduce the Tramp to get into the story.”

Born into poverty in 1889 London, Chaplin died on Christmas Day 1977. Eyman’s Chaplin is forever stunted by the horrors of his youth.

“That was the source of the Tramp’s attitude towards the world. And to a great extent it was also the source of Chaplin’s attitude towards women,” Eyman said. “Because of his childhood he had an inbred distrust of society. He simply didn’t believe that society had any interest in the individual. Not out of cruelty but basic indifference.

“He thought it was just a question of inbred selfishness really. So the Tramp has to always depend upon himself.

“And Chaplin, in his own mind, had the same quality.  He trusted (the silent movie star) Douglas Fairbanks, who was his best friend, but Fairbanks died young. He trusted his brother Sydney and he trusted his wife Oona. And that’s about it.”

As to where you go after being immersed for years in this titan of world cinema, “I’m not 100% sure, but it’s going to be a woman,” Eyman promised.

“I need to write about someone who is slightly more emotionally accessible. And I haven’t written about a woman in 30 years. So I’m way, way, way overdue.”