Grand Admiral Thrawn and Darth Vader team up against a threat to the Empire in this thrilling novel from bestselling author Timothy Zahn.

"I have sensed a disturbance in the Force."

Ominous words under any circumstances, but all the more so when uttered by Emperor Palpatine. On Batuu, at the edge of the Unknown Regions, a threat to the Empire is taking root--its existence little more than a glimmer, its consequences as yet unknowable. But it is troubling enough to the Imperial leader to warrant investigation by his most powerful agents: ruthless enforcer Lord Vader and brilliant strategist Grand Admiral Thrawn. Fierce rivals for the Emperor's favor and outspoken adversaries on Imperial affairs--including the Death Star project--the formidable pair seem unlikely partners for such a crucial mission. But the Emperor knows it's not the first time Vader and Thrawn have joined forces. And there's more behind his royal command than either man suspects.

In what seems like a lifetime ago, General Anakin Skywalker of the Galactic Republic and Commander Mitth'raw'nuruodo, officer of the Chiss Ascendancy, crossed paths for the first time. One on a desperate personal quest, the other with motives unknown . . . and undisclosed. But facing a gauntlet of dangers on a far-flung world, they forged an uneasy alliance--neither remotely aware of what his future held in store.

Now, thrust together once more, they find themselves bound again for the planet where they once fought side by side. There they will be doubly challenged--by a test of their allegiance to the Empire . . . and by an enemy that threatens even their combined might.