The Twilight Prisoner — Katherine Marsh

After traveling to the underworld and back to the realm of the living, Jack Perdu tries hard to fit in at his new school -- and to win the affections of his classmate Cora. In an effort to impress her, Jack leads Cora to the entrance of the underworld and makes a terrible mistake. Soon they have crossed the threshold -- and there may be no getting back.

Like The Night Tourist, this exciting sequel blends together the modern-day world and mythology -- this time cleverly introducing readers to the myth of Persephone and Eros.