Doors into chaos - Robert Greenberger

More than 200,000 years have passed since the Iconians first created the network of interdimensional gateways across the stars. Known to those who came after them as 'the Demons of Air and Darkness', the Iconians vanished from time and space millennia ago -- or did they?
Summoned to an emergency briefing at Starfleet Headquarters, Captain Jean-Luc Picard is stunned to discover that the legendary Iconians have returned at last, and are offering to sell the secrets of their long-lost technology to the Federation. To prove their sincerity, they have reactivated their dormant gateways...but the result has been conflict and chaos throughout the Alpha Quadrant. Warring Klingons and Romulans are among the hazards Picard and his crew must contend with as they seek to discover the sinister truth behind the Iconians' mysterious return.