Call to Arms is the sixth book in the epic 'Nexus' series, part of the growing Star Crusades universe that chronicles humanity's first steps away from Alpha Centauri and beyond. The Great Biomech War is now inevitable and the citizens of the Alliance ready themselves for what is to come. Ships and soldiers from a hundred worlds set their eyes on Helios, some looking to defend it and others making their plans to bring about its destruction. As each day passes, the defenders around Helios grow, and each day brings the prophetic comet closer to them. The remaining Biomechs have their own plans, and worlds as far away as Earth now feel their wrath.