What Lay Beyond (2001)

Amazon.com Product Description (ISBN 0743456831, Mass Market Paperback)

As each character finally discovers the secrets that lie beyond the interstallar portals, the Gateways saga is brought to a magnificent and compelling conclusion. Created by an incalculably ancient civilisation whose transcendent technology is quantum levels beyond that of the Federation and its allies, the newly discovered Gateways offer instantaneous transportation across the stars. Their sudden reactivation has destabilised relations between planets and cultures hitherto separated by countless light years. Starfleet's finest have coped with the crisis as best they can, but circumstances have forced a handful of valiant commanders, one after another, to make the leap through separate Gateways into the unknown. Each of these brave heroes has taken the ultimate gamble and hurled themselves bodily into a Gateway with no knowledge or forwarning of what they will find on the other side. Each must face a unique personal challenge and find their own way back to the ships and the homes they left behind. And beyond at least one of the Gates are their mysterious and primordial architects, the ageless Iconians themselves...