The Quadrail Series Books 4–5: The Domino Pattern and Judgment at Proteus

This collection contains books four and five of Timothy Zahn's Quadrail series, combining action, science fiction, mystery, and espionage. The Quadrail is an intergalactic transportation system created and maintained by the alien Chahwyn, who built the Spiders to ensure its safe operation. Ex-government agent Frank Compton works to protect the system's integrity alongside Bayta, his half-human, half-Chahwyn partner. Together they have worked to keep the Quadrail open and prevent the Modhri, a parasitic species that spreads mind-controlling infection, from exploiting it. In The Domino Pattern, passengers aboard the Quadrail are being poisoned while it travels toward the galaxy's farthest edge. Compton and Bayta must uncover a sinister conspiracy to prevent the system from derailing and stop the ordered universe from descending into chaos. In Judgment at Proteus, the Shonkla-raa—invincible fighters thought to be extinct—have resurfaced with plans to destroy the Quadrail. Compton and Bayta must ally with the Modhri, their most feared enemy, to protect all species along the Quadrail from annihilation.