The Dark Prophecy by Rick Riordan

Go west. Capture Apollo before he can find the next oracle.
If you cannot bring him to me alive, kill him.

Those were the orders my old enemy Nero had given to Meg McCaffrey. But why would an ancient Roman emperor zero in on Indianapolis? And now that I have made it here (still in the embarrassing form of Lester Papadopoulos), where is Meg?

Meg, my demigod master, is a cantankerous street urchin. She betrayed me to Nero back at Camp Half-Blood. And while I'm mortal, she can order me to do anything . . . even kill myself. Despite all this, if I have a chance of prying her away from her villainous stepfather, I have to try.

But I'm new at this heroic-quest business, and my father, Zeus, stripped me of all my godly powers. Oh, the indignities and pain I have already suffered! Untold humiliation, impossible time limits, life-threatening danger . . . Shouldn't there be a reward at the end of each completed task? Not just more deadly quests?

I vow that if I ever regain my godhood, I will never again send a poor mortal on a quest. Unless it is really important. And unless I am sure the mortal can handle it. And unless I am pressed for time . . . or I really just don't feel like doing it myself. I will be much kinder and more generous than everyone is being to me--especially that sorceress Calypso. What does Leo see in her, anyway?

This book is part of the "The Trials of Apollo" series.
Here are some other books from this series: