The Four Horsemen -- and the rest of the Merc Guild -- have spent years preparing for the Kahraman. Building their militaries. Equipping them with the best arms and armor. But when Jim Cartwright goes to the Fourth Arm, he finds out that the Kahraman aren't the ones to worry about.

The Synthetic Intelligences, or SIs, are.

A cabal of Type 5 SIs have been running the guilds for millennia, guiding society and trying to make it into a more "peaceful" place. But they've decided that the biological races will never be peaceful unless the SIs intervene to make them so.

For centuries, they've been building an army of pacified beings and OogSha shock troops in the Fourth Arm with one goal -- to take over every planet in the other three arms, kill the inhabitants, and replace them with their pacified citizens.

The invasion is on, and it's up to the Four Horsemen to organize a defense and kill the Type 5s in their fortress under Capital Planet. But with the SI invasion already in progress and planets being conquered across the galaxy, will they be able to muster the forces required to do so before the SIs take over?

It's no longer just the "Four Horsemen for Earth" -- this time, it's for the galaxy, because if the SIs aren't stopped, life as we know it will end, and all sentient biological life in the galaxy will be replaced!

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• Publication Date: March 25, 2026
• Text-to-Speech: Disabled
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• Print Length: 385 Pages
• File Size: 38 KB