John can hear that note in Jim's voice, the panic beginning to set in, and he feels somewhat guilty for having caused such a thing. This had been their agreement, and if Jim had been the one to enter the cave instead of him, John would not be content to stand outside that barrier and do nothing himself. But the alternative...?

"My dear," John says, shakily. "I do appreciate your concern. But what else do you propose that I should do? While I stay within this barrier, the corruption is still contained. So long as the quarantine is maintained, no others outside of this cave will need to suffer. The city..."

He shakes his head at the other man. "We cannot allow it to reach the city, James. We cannot."