Episodes of strange, chilling deaths that defy reason and boggle the mind in their shocking distinctiveness erupt in major American cities in The Happening. All images ™ & © Twentieth Century Fox.

M. Night Shyamalan has built his reputation on mind-blowing twists, and gut-tensing suspense. But his new film The Happening (opening today from Fox) is like nothing the director has attempted before.

In The Happening, the world and nature get their revenge for decades of pollution and mistreatment, and within a span of hours puts the future of mankind at risk. Unlike the director's previous films, The Happening is R-rated, which freed Shyamalan to go for broke when it came to creating disturbing images.

Famously skeptical of digital effects, Shyamalan did as much as possible in frame, using wind machines, mechanical special effects and on set pyrotechnics whenever possible during the film's 44-day shoot last year in Pennsylvania.

For effects that couldn't be created on set, Shyamalan turned to VFX houses such as ILM and CafeFX, which created a number of memorable and gory sequences for the film.

David Ebner, vfx supervisor for CafeFX on the film, says Shyamalan's overriding goal for visual effects is that they be as convincing as possible.

"He's very critical of visual effects movies in general, Ebner observes. He has a discerning eye and he wants everything to look real."

Accomplishing that took a lot of work on what Ebner says was CafeFX's most difficult sequence: a scene in which a group of zoo lions turn on their tamer and rip his arms off. The scene was short but complex, requiring previs and planning with the special effects and prosthetic effects crews to figure out how best to shoot it when safety requirements won't allow an actor to be alone on set with more than one lion at a time.

"And then we found out we couldn't actually use fake blood material either, because that would just get the lions going crazy, even if it wasn't real, Ebner adds. "So we started planning that all that would be done in computer graphics as well."

In the shot, the lion tamer offers his hand out in friendship to the lions, only to have them attack. On set, the actor was offering the lion a prosthetic arm on a rod that he was controlling with his other arm.

"The part that gets ripped off is fake, but what we had to do then is patch the fact that you could see his other arm not doing the right thing," Ebner continues. That involved removing his arms, the rod and replace the actor's shoulders and back. That was probably one of the harder parts of the job, was to cover him up.

CafeFX had to add all the details of the lion's attack, showing the skin ripping off the arm, the internal structure of the arm and then the arm coming off at the elbows. When the actor falls to the ground, bloody stumps had to be added, as well as the spraying, pooling blood.

Ebner says some of the blood was painted on the ground and then covered up and revealed slowly in compositing. Live action blood elements were filmed at CafeFX's studio and asome CG fluid simulation was used as well to get the right look.

The result turned out to be a bit much for a film that at the time had not yet gotten studio permission for an R rating. The amount of blood pouring out or dripping out of his stumps was kind of tamed down a bit by the director, says Ebner. It was an aesthetic choice.