The Icarus twin

"For years Gregory Roarke and his Kadolian partner Selene worked as crocketts, combing through the atmospheres of uninhabited worlds for places that might be colonized or hold valuable resources. Now, they quietly work for the Icarus Group, a top-secret government organization hunting for portals created by a long-vanished alien race, portals that can teleport a person hundreds or thousands of light-years in the blink of an eye. Roarke and Selene...