"That would be the one. He got like that because his mother dipped him into the River Styx to make him invincible when he was a baby and forgot to get his heel wet. Now people can go down there and do the same thing--only their 'heel' would be a place of their choosing that would anchor them to humanity," Luke explained. "If you don't focus hard enough on something that makes you glad to be human the river will burn you alive."

"I've gotta go do that," Luke finished, wondering if this was too weird for even Kate to take.