When he was having dinner with his grandfather and the latter's guest, Ghost received the message from Lee. Unknown to anyone else, Lee was the spy that Ghost placed near Luo Yin to gather the shreds of evidence of all the crimes that he did when he was abroad.
Without waiting any longer, he immediately texted Callum the room number. Earlier, Callum informed him that he was on the way to Hotel Royale with Kai An to look for Naomi Nakamura.
From what Callum told him over their daily conversations, he knew that Kai An was actively courting Naomi Nakamura and he wanted to help out. After all, he was Kai Xin's brother.
Over the years, he had been watching in the dark unable to do anything, but his hands were no longer bound. It was time for him to speed things along.