One of the major milestones in comic book history came in May 1975 when a very young writer with an interest in acting, Chris Claremont, took over penning the exploits of a band of mutants in Marvel's "Uncanny X-Men." He got the job because of his enthusiasm for the characters and because the comic was doing so poorly in circulation that veteran writers had little interest.

What happened after is the subject of Patrick Meaney's documentary "Chris Claremont's X-Men," available through Video on Demand starting Tuesday. The film is an extended version of the director's 2013's "Comics in Focus: Chris Claremont's X-Men." Officially, the book and band of heroes are Marvel's "X-Men," but Claremont made such an impact on the book and the comic industry over the next 17 years that the comic book title was transformed by Claremont's embracing of change and the respect he showed for the readers.

Not only did Claremont save "Uncanny X-Men" from cancellation, he turned it into the company's biggest hit. The success can be measured in the influence his writing had as his story lines have been used to create 10 films and TV series. It can also be measured in how Claremont changed the way comics were written, implementing complicated plots, delving deep into the psychology of human emotions and pushing for more of an emphasis on female characters by moving them into leadership levels.

He offers a few glimpses into the process that made him one of the most successful comic book writers. On the question of what audience he was writing for with his intelligent and detailed stories, Claremont says it was a simple approach that worked.

"My ambition was very fundamental," he says. "I wanted to grab every set of eyes, every brain and member of the audience who was out there. The only way to do that was to tell stories and create characters and put them through hell in ways the readers found irresistible."

Enough time has passed since he was taken off "Uncanny X-Men" in 1991 that Claremont is able to talk about how he feels about the way the run ended. In the film, he calmly talks about how corporate changes ended up being the death knell for his days with the X-Men.

"If this documentary had been filmed in 1992, I suspect my attitude would have been completely different," he says. "The fact is that [stuff] happens. These are Marvel properties, and because they sign the paychecks they reserve the right to make its own decision in regards to its own titles and by extension to its talent.

"My mistake was assuming my tenure and my demonstrative success insulated me from that kind of concern. From Marvel's perspective, the longer I stayed where I was and the more successful the title became, the more of a fear grew at the corporate point that the book could be viewed as Chris Claremont's 'X-Men' and not Marvel's 'X-Men.'‚ÄČ"