In 1984, at the dawn of the personal-computer era, novice software tester Roberta Walton stumbles across a bug. She brings it to its inadvertent creator, longtime programmer Ethan Levin, and the two embark on a hunt for the elusive bug, nicknamed “The Jester” for its tendency to appear randomly and only at the least opportune moments, jeopardizing the fate of the company. Ethan’s attempts to find a solution soon become a frightening obsession that threatens to destroy both his professional and personal life. Roberta, on the other hand, is drawn to the challenge. Forced to learn how to program, and seeking refuge from her own private troubles, she becomes enthralled with learning to speak the computer’s language. Expertly merging code with prose, big ideas with intensely personal stories, Ellen Ullman brilliantly illuminates the space between human beings and computers—a space we occupy every day as we peer into our monitors.