“And you, Hazel,” Aphros said, “come visit again, and bring that horse of yours! I know you are concerned about the time you lost, spending the night in our realm. You are worried about your brother, Nico.…”
Hazel gripped her cavalry sword. “Is he—do you know where he is?”
Aphros shook his head. “Not exactly. But when you get closer, you should be able to sense his presence. Never fear! You must reach Rome the day after tomorrow if you are to save him, but there is still time. And you must save him.”

The Mark of Athena, Chapter XXIV