NEW YORK (AP) — Rick Riordan (RY'-ehr-dan) is taking on a new set of gods.
 

The author of the million-selling "Percy Jackson" children's books says he's going to write a series based on old Norse tales.
 

He expects the first book to come out around 2015.

In the meantime, he's still writing stories for his Greek-influenced "Heroes of Olympus" series and for the
Egyptian-themed "Kane Chronicles."
 

His latest novel, "The Son of Neptune," the second of his Olympus books, comes out Tuesday and has already topped the best-seller list on Amazon.com.

Riordan revealed his plans for the Norse books during a weekend interview with The Associated Press.