Atop an elevated train barreling through Downtown, the masked man in the red and blue suit is in trouble.

Not only is he fighting a lunatic scientist who's trying to kill him with robotic tentacles, but he also needs to save the passengers on the train. It's all in a day's work for superhero Peter Parker, also known as Spider-Man -- but it means months of work for an elite team of graphics gurus.

This action sequence from the megahit Spider-Man 2 has dazzled millions of moviegoers this summer. Look closely at the villain, Doctor Octopus (played by actor Alfred Molina), and you'll see him grin maniacally and yell while ambulating along the top and sides of the train. Later in the scene, Spider-Man (Tobey Maguire) loses his mask as he braces himself against the front of the train, bringing it to a screeching halt. His frantic facial expressions appear convincingly natural.