The Hand of Thrawn

The Hand of Thrawn duology by Timothy Zahn
The thrilling follow-up to Timothy Zahn's beloved Thrawn Trilogy! Ten years after Grand Admiral Thrawn nearly brought the New Republic to its knees, the Imperial Remnant is ready to finally surrender to the former rebels. Not everyone would have peace: Three well-placed Imperials conspire to fake the resurrection of Thrawn, not realizing how close to the truth they really are. Luke Skywalker and Mara Jade follow a mysterious trail of clues to a shocking discovery the Unknown Regions, while a revelation from the past threatens to tear the New Republic apart from the inside.

Buy on Amazon:
Book 1: Specter of the Past
Book 2: Vision of the Future

This is a post-Return of the Jedi series from the Legends timeline. Think of it as an alternate universe from The Force Awakens and newer books.