At 8:30 A.M. on November 24, the Monday before Thanksgiving, Amy Pascal arrived in her office in the Thalberg building, on the Sony Pictures lot, in Culver City, California. Pascal, 56, is among the most powerful people in Hollywood. Having spent 35 years in the trenches—from low-level secretary to her current job as co-chairman of Sony Pictures Entertainment, the global television-digital-and-motion-picture conglomerate—she has earned the expansive third-floor office that was occupied by studio head Louis B. Mayer, in the 1930s and 1940s, when the Sony lot was the domain of mighty Metro-Goldwyn-Mayer, and Mayer was known as “the Lion of Hollywood.” It was on these soundstages and movie sets that Atlanta was burned in Gone with the Wind and Dorothy followed the Yellow Brick Road to Oz. Since Sony and a consortium of investors purchased MGM, in 2005, its films have earned 142 Academy Award nominations, 10 of them for best picture.

The studio’s secrets were safe in Mayer’s day, when they died within the walls of a soundproof telephone room adjoining his office. Pascal believed she didn’t need the soundproof room. Like everyone else in the entertainment industry these days, she communicated through e-mail that was believed to be secure. But this morning, as she began her day, she discovered that a bizarre specter had hijacked her computer. The screen glowed with a blood-red skeleton baring its fangs, and the words “Hacked By #GOP.”

Superimposed over the skeleton was an ominous warning:

We’ve obtained all your internal data including your secrets and top secrets.

If you don’t obey us, we’ll release data shown below to the world.

The “data” below consisted of five links that would turn out to be the internal records of the entertainment giant.

Pascal thought it was a joke. Still, she called Michael Lynton, 55, Sony Pictures’ C.E.O. and chairman, who occupies an office down the hall. He and Pascal have been a team for nearly a decade now; Lynton handles administration and business affairs, leaving Pascal free to deal with the creative side of making movies.

Lynton told her he’d been advised of the skeleton’s threat while driving to the studio that morning, having received a call from Sony’s C.F.O., David Hendler, who explained they’d been hacked by an organization called Guardians of Peace. They were shutting Sony’s entire computer system down, including the network, Internet, and any customer-facing sites, to stop any further damage.

On the previous Friday, November 21, Lynton, Pascal, and several other Sony executives had been sent an e-mail from a group calling itself “God’sApstls,” which included a demand for “monetary compensation” and to “pay the damage, or Sony Pictures will be bombarded as a whole.” On one of the company’s Twitter feeds, the same group had posted a crude depiction of Lynton and Pascal as ghouls in a surreal doomsday backdrop, along with a warning: “You, the criminals including Michael Lynton will surely go to hell. Nobody can help you.”

Neither Lynton nor Pascal had seen those messages—Lynton’s had become lost in his in-box; Pascal’s had gone to her spam.

Now what the 3,500 employees on the lot had started calling “the screen of death” flashed on every computer that was turned on in the massive Sony Pictures Entertainment network worldwide. Employees were instructed to immediately turn off their computers and ensure that their phones and tablets were disconnected from Wi-Fi and not to engage in e-mail or download anything on the company lot.