When Doctor Annia 4424 first isolated the dormant retrovirus, she thought she had uncovered a harmless fragment of DNA. By the time she realized what she had really found, her discovery had triggered an alarm. Century Plague was so virulent it had twice threatened to wipe out galactic civilization, and even to study it in simulation carried a Federation death sentence. But Annia knows something no one else does. The virus wasn’t eradicated with the firebombing of the infected worlds. It is programmed to come out of dormancy and spread again across a defenseless galaxy.