Heroes of Olympos at Hogwarts (Pernico/percico/Nicercy)

Hecate shows up at camp half-blood along with Farank, Hazel and Reyna. She gives the seven, Nico and Reyna a quest. They have to travel to the past and on top of that to Scotland to a school called Hogwarts. Apparently the school is for wizards and witches. They have to help them to win a war that ended badly for them the first time around.