Mission Beyond The Stars: Book #1 of "Saga Of The Lost Worlds" by Neely and Dobbs
Two populated solar systems of the Kepren Cluster Alliance mysteriously vanished. The frantic Alliance leaders’ desperate evacuation plan was adamantly rejected—until a third system vanished. Later a lone planet vanishes; its freed moon may destroy Kepren, dooming billions. A select team must return, resolve a cosmic intrigue, confront a conflict of universes, and strive to prevent disaster.