remain vulnerable. This is the point where your soul will anchor your body to

the world. It will be your greatest weakness, but also your only hope.

 

No man may be completely invulnerable. Lose sight of what keeps you mortal, and

the River Styx will bum you to ashes. You will cease to exist."

 

"I don't suppose you could tell me Luke's mortal point?"

 

He scowled. "Prepare yourself, foolish boy. Whether you survive this or not, you

have sealed your doom!"

 

With that happy thought, he vanished.

 

"Percy," Nico said, "maybe he's right."

 

"This was your idea."

 

"I know, but now that we're here — "

 

"Just wait on the shore. If anything happens to me . . . Well, maybe Hades will

get his wish, and you'll be the child of the prophecy after all."

 

He didn't look pleased about that, but I didn't care.

 

Before I could change my mind, I concentrated on the small of my back — a tiny