For over 100 years, the Four Horsemen have fought aliens across the galaxy, while simultaneously keeping Earth safe from the aliens who wanted its resources. It turns out, though, they were too efficient. The galaxy-ruling guild masters, the surviving synthetic intelligence (SI) doomsday weapons used to end the Great Galactic War 20,000 years ago, have decided biological life is too dangerous. Instead, they aim to replace all intelligent life with ‘gentled’ versions that are incapable of violence. The only thing that stands in the way are the Four Horsemen. Several of the SIs managed to escape after the cataclysmic battle on Capital, leaving behind a devastated planet and a tear in the fabric of space-time, and the Horsemen must race against time to finish off the SIs. The only problem? The SIs’ final base is on Earth. Now all humanity is on the line, and even if the Horsemen succeed in terminating the SIs, the team trying to close the tear faces a nearly impossible task. This is the final battle. It has all come down to this, and as the final seal is opened, all that may remain is a Silence in Heaven.