“I went to a person close to him and said, ‘This guy is in serious trouble with serious drugs. We’ve got to help him,’ ” Mr. Arnold recalled in an interview. “And this person flat-out told me to my face, ‘We make a lot of money from him. I can’t be part of it.’ That tells you everything you need to know.”…

It was not the first time that the show’s managers had tried to intercede, but they had limited options: Mr. Sheen’s contract does not include any kind of morals provision that would have allowed him to be fired or replaced. According to one longtime Hollywood agent (who, like many people quoted in this article, spoke on the condition of anonymity so as not to create any conflicts in their business), the show’s success had provided him with the leverage he needed to keep any such clause out.

“He’s money,” this agent said. “He makes the cash register ring.”…

Mr. Abrahams said Mr. Sheen was quite open about his drug abuse at the time, even opening up about the toll it had already taken on his mind. “He told me that he would look at movies he had done and not remember having done entire scenes — not because he was under the influence while acting, but because the partying had started to take a toll on his overall memory.”