In the future, a band of immortals (some who are famous historical characters, some who have tried their best to avoid becoming so), including Herb Wells, Ned Curzon (nicknamed Grand Guignol), Hillel, and Sam Pepys have only one requirement for membership: don't die. Through their extensive social network, they come across a brilliant Cherokee physicist named Sequoya Guess, who himself has only very recently learned of his peculiarity and the catches and loopholes that come along with it. This creates a swift change in Guess's day-to-day life that is as much a shock to his friends as to himself. At the same time, the world's scientists are collaborating to bring together a supercomputer named Extro that will monitor and control all mechanical activity on Earth. The immortals create a plan to subtly harness Extro to aid them in their quest for knowledge and use some of the experience they've gained to assist it in its task. Working outside of expected behavior, Extro instead seizes control of Dr. Guess, leaving the only people who know what's going on — the Immortals and Guess's nearest friends — to grapple with the heart and mind of a malevolent machine in the body of an Immortal, a powerful and ingenious man who cannot be killed.