"You can't kill me," growled Bruce. He had been stupid enough to allow himself to be captured - and he would have to resort to desperate measures to avert permanent failure.
"I'm not going to kill you," said his nemesis, pointing to the terrified, unwilling participant standing next to Bruce on the bridge. "But he might."
Bruce could hear the trolley coming closer. If he didn't do something soon, one of two things would happen. Either the five people on the tracks would die, or Bruce would be pushed off the bridge to stop the trolley with his body. Neither was acceptable. If he died, he would protect these innocents - maybe - but others would doubtless die in future experiments. If he did not stop the trolley, then five people who had not signed consent forms or waivers of liability would be killed, in an unauthorized experiment.
The only way out was to take advantage of the villain's weakness by revealing part of his secret - and he could only pull this trick once.
"You can't let anyone die tonight, because then you'll never learn my secret."
"Your real name?" The man who called himself the Joker turned his toothy grin directly toward him. "You're funnier than I thought. Your secret! As if the person you are by day is the same person as the one inside that bat suit of yours."
"No. My experiment." Now he had the Joker's interest. "Every night, I've dressed as a bat. I've hung upside down in a cave with them. I've glided through the air using the Bat-Cape as a wing. Ever wondered why your attempts to confound my night goggles don't work? It's because they're not using light at all; they're using Bat-Sonar.
"You involve other people in your experiments; I've taken the moral route - but you can learn a lot through self-experimentation. So aren't you the least bit curious? Don't you want to abandon this experiment, just this once, to hear the answer to the famous problem?"
The joker made a gesture to one of his henchmen, who walked off the bridge. A few moments later, the trolley stopped. After a long silence, the Joker spoke.
"All right, I'll ask. What is it like to be a bat?"