Everything you need to understand or teach Press Enter by John Varley.
The premise is a common one in science fiction. Somewhere, computers have acquired intelligence and have learned how to murder those who uncover their secrets. As Foo explains, it is "the old 'critical mass computer' idea, the computer that becomes aware, but with a new angle. Maybe it wouldn't be the size of the computer, but the number of computers." Apfel asks her, "Wouldn't it ... run our lives? . . .
Would it take over?" Foo...