The new crossover story is called The Crown of Ptolemy. It brings the joint effort of the four fantastic main characters from said two series: Percy Jackson, Annabeth Chase, and Carter and Sadie Kane. If you'd like to read a sampler, you could head over to Hypable.
What can you say about the new cover of The Crown of Ptolemy By Rick Riordan?
In their first encounter, demigod Percy Jackson and magician Carter Kane had to battle a giant crocodile on Long Island. A month later, Annabeth Chase ran into Carter’s sister, Sadie, on the A train to Rockaway, where the pair fought a god named Serapis. Now trouble is brewing again, this time on Governor’s Island. An ancient Egyptian magician named Setne has come back from the dead and is experimenting with Egyptian and Greek magic, trying to become a god himself. He’s so powerful and tricky that all four—Percy, Annabeth, Carter, and Sadie—have to team up against him. But their usual weapons and spells aren’t going to cut it this time. Will the heroes be taken down by a wannabe god who looks like Elvis, or will they rise to the challenge? Told from Percy’s point of view, this third demigod-magician crossover story has all of the spunk and action that Rick Riordan fans crave.
The Crown of Ptolemy by Rick Riordan will be published in the following dates: trade paperback edition of The House of Hades, March 31, 2015; and eBook and Amazon editions, May 12, 2015.