What if the Emperor of Mankind was in The Promised Neverland?

As Emma Ray & Norman plot their escape, a mysterious man shows up at Gracefield uninvited.
Our waifu Isabella slowly finds out who he is & why he's here. He reveals the human side of the world has been united under a new empire, & the Emperor is going to break the Promise & finish the war once & for all. This man is here to get the children to the human side before the emperor's forces ravage the land.
He downplays himself as a secret agent on a rescue mission, but our waifu & Norman suspect he is much more than he's letting on.
But they don't have much time. Thanks to his negligence he alerted security before he even got to the door.
Will Isabella & the children be slaughtered now that they know the truth? Or does this man have a way to back up his smug bravado?