Star Wars: Survivor's Quest by Timothy Zahn
Luke Skywalker and his wife, Mara, get a strange message from the Chiss: Come and get the remains of the mysterious Outbound Flight Project. But there is more than meets the eye to this unexpected gift, as the newlyweds come face to face with the past! For someone is still alive in the Outbound Flight ships, and they're not interested in visitors. Plus there's at least one imposter along on the mission, and maybe more, and it will be up to Luke and Mara to uncover all the secrets and prevent another war from breaking out.