The story behind “The Man Who Killed Don Quixote” and its impact on director Terry Gilliam will be revealed in the new documentary “He Dreams of Giants,” a film-behind-the-film from the same team that made 2002’s “Lost in La Mancha,” an earlier look at Gilliam’s disaster-plagued movie.

Keith Fulton and Louis Pepe direct “He Dreams of Giants,” which follows “Lost in La Mancha” and “The Hamster Factor and Other Tales of Twelve Monkeys.” The pair were on set for “The Man Who Killed Don Quixote,” which is closing the Cannes Film Festival amid a protracted legal battle. The fest has called the film a “unique — and in some ways agonizing — work.”

U.K.-based Quixote Productions, Fulton and Pepe’s Low Key Pictures, and Corniche Pictures are producing “He Dreams of Giants.” Lucy Darwin produces alongside Fulton, and is in Cannes talking to sales agents about the film, which is being edited. Ari Ioannides exec produces and provided the funding for “He Dreams of Giants” to go into production.

The filmmakers told Variety that they have taken a wholly different approach from “Lost in La Mancha.” As well as the cinema verite elements on the drama of making the movie, they sought to capture what was going on in Gilliam’s head.

“We began to think this is more a film about an internal struggle in an artist’s mind,” Fulton said. “What is it like for an artist to be standing on the brink of actually finishing this project finally?”

Pepe added: “Even on the set we would say the conflicts raging around Terry right now of making the movie are not nearly as interesting as what’s going on inside his head.”

There is archive footage and extensive interviews with Gilliam. Fulton and Pepe also employed a “mindscreen” technique whereby they shot Gilliam’s face, revealing his reactions to what was happening around him. These shots became the core of “He Dreams of Giants.”

The filmmakers tuned into the off-screen drama surrounding the film, but it is not central to their doc. “We certainly touch on it in our film and acknowledge it, but it always struck us that it wasn’t as fascinating as this deeper 27-year push,” Fulton said.

Gilliam has endured reported health scares, including a recent mini-stroke. Pepe said the director was “completely depleted” at the end of production but has been in fine fettle since, despite the ongoing controversies surrounding his film. “I’ve noticed his spirits have certainly been plucked up again by all of this conflict,” Pepe said. “[It] is the opposite of Kryptonite for him. It totally feeds him.”