If you lived long enough, this could be your future, too

It is the late 21st century, and it is a very different world. Little is as it used to be, and many are not what they seem. Kendrick Gallmon, survivor of an infamous secret research facility called the Maze, is trying to pick up the pieces of his life, even though he knows his nervous system, which is riddled with unstable nanotech augmentations, is slowly killing him. Then one day his heart stops beating, forever, and a ghost urges him to return to the source of all his nightmares, a long-abandoned military complex filled with entirely real voices of the dead.