Asimov's Three Laws of Robotics:

I) A robot may not injure a human or, through inaction, allow a human being to come to harm.

II) A robot must obey the orders given it by human beings except where such orders would conflict with the First Law.

III) A robot must protect its own existence as long as such protection does not conflict with the First or Second Law.

"So, that's basically it," inspector Cragg concluded, "They are being held hostage by a robot."

A loud uproar among the officials from the International Robots Corporation followed this announcement. Cragg twisted his face in despair. He had known that it would eventually come to this. After all, whoever had ever heard of a killer robot?

"Please!" Cragg exclaimed with his hands raised, urging everyone to quiet down and failing miserably. "Please! I know it's hard to believe but it is a robot out there! The thermal scan we took of the bus proved it. The person holding the passengers hostages has an outer temperature of twenty degrees while concentrated at the very middle of his chest the temperature is as high as a few thousand degrees – something that only a mini thermonuclear fusion reactor could produce. And only robots are equipped with that sort of reactor … with the reactor usually installed in their chests."

"But this is outrageous!" claimed Dr. Rinnard, a roboticist, "A robot wouldn't kill. It can'tkill! The First Law doesn't allow it to kill!"

"I know Dr. Rinnard–––"

"Rinnard!" claimed a crisp, female voice that cut off Cragg's own, "Quiet down!"

Rinnard turned and looked straight into the face of Cynthia. He turned away quickly, however, unable to level with the latter's icy stare.

"But listen to what he's saying!" Rinnard protested, his eyes locked with those of Cragg, "How could a robot ever kill?"

"But it did. It trained its blaster at the unfortunate driver and pulled the trigger," Cynthia retorted.

"But … but … how? How could this be possible?"

A hush fell over the place.

"I believe I know how," Cynthia said. Rinnard stared open mouthed at her in disbelief. Shaking her head, she continued, "Sometimes, I do wonder how you ever managed to become a roboticist, Rinnard. I'd been expecting something like this. Why do you think the police called us – you a roboticist and me a robopsychologist – to help in the case of hijacking? It could only mean that robots were involved. And a robot could never be involved in such a case like this, which involves harming humans, unless it was devoid of Asimov's First Law of Robotics."

It took a moment for what Cynthia had said to sink in. What followed was a greater uproar. Rinnard stood silently, staring at Cynthia, shaken by what he had heard. A robot devoid of the First Law? A robot that could kill and had already done so…

"Excuse me! Everyone!" Cynthia strained herself to be heard, "I have not finished!"

It took a while for everyone to quiet down. Cynthia continued, "Now, I know what I've said might sound crazy but it isn't entirely impossible. It is, in fact, easier to make a robot without the First Law than a robot with one. It is just like making a bicycle without brakes. I will not go into details because it involves a lot of mathematical figures and all those complex words which would probably be meaningless to you.

"About the robot; the mere fact that it has killed a human, the bus driver, is enough evidence that it is not governed by the First Law. However, we can be certain that the robot retains the Second and the Third Law, for up until now no robot has been created which was intelligent enough to commit such an act on its own… Inspector Cragg, have you identified which model the robot is?"

"It's an Anaret model, doctor."

"An NR8, eh? There you go! That robot is pretty primitive. Not even as intelligent as those last 9NA models. Replacing its positronic brain would not help for it can't even accommodate that of the 9NA's. So, it's obvious that the robot has hijacked the bus under orders from a human; a human capable enough of making a positronic brain without the First Law. That human could only be a roboticist."

"But how does all that information help us?" Cragg asked, "We need to stop that robot and save the passengers. We've already flooded the bus in gamma radiation for five seconds straight in hopes of frying that robot's brain. But nothing happened. Instead, the robot then killed the driver. No doubt the robot was covered in anti-radiation film. We could eventually fry that bastard's brain if we continued flooding the bus with the radiation for over longer periods of time, but the over-exposure to radiation would eventually kill the passengers too. The only thing we can do now is provide the robot with the ransom it is asking for."

"Did you try talking to the robot?" Cynthia asked.

"We did. It's like a bloody tape recorder though. Every time it threatens to kill a passenger if we delay in giving it the money it is asking for."

Cynthia pondered for a moment. "Then it should be under strict – very strict – orders from whoever programmed him, to be able to disobey any kind of order from another human being …"

"Cynthia?" Rinnard asked.

Cynthia looked up suddenly. "How much ransom has he asked for inspector?"

"What, eh?" Cragg hesitated, taken by surprise, "Oh, a hundred million credits."

"A hundred million credits … Well I think it's time we gave it to him. And if you don't mind, I'd like to be the one to give it to him."

...

At a radius of about a hundred meters, the police circled the bus, their guns trained and their fingers on their triggers. Inspector Cragg had ordered them to open fire the instant the robot got out of the bus though Cragg was sure that the damage to the robot would not be enough to prevent it from escaping. He had ordered them to fire below the knee level to ensure that no bullets strayed into the bus and hit a passenger. Or worse, Dr. Cynthia Astylar, the robopsychologist from International Robots Corporation.

She had been resolute about giving the ransom to the robot herself, despite discouragement from Cragg himself, Rinnard and the rest of the police force. Despite their nagging, she had been absolutely mum as to why she wanted to give the ransom herself.

"You blokes called me to deal with this robot. So, this is me dealing with it and I advise you deal with my decision," she had said.

After news had come to them that the robot had killed another passenger, a man of about fifty, Cragg had given in. The robot had to be stopped somehow, from killing anyway, and no one was willing to go into the bus and offer the ransom to that homicidal piece of tin. And besides, Cragg thought Cynthia had something in her hard-to-crack mind.

That had been about an hour ago. Five minutes had passed since Cynthia had entered the bus. Up until now, nothing had happened and Cragg was growing worried. What the hell was going on inside?

Cragg almost jumped when the door handle of the bus turned. "Ready men! On my ––"

His mouth fell open when Cynthia walked out the door, a line of shaken passengers following her.

...

"Have you retrieved the robot?" Cynthia asked.

"Yes, doctor," Cragg replied.

"Destroy it," Cynthia said flatly.

"What?" Cragg exclaimed, his eyes wide.

"Destroy it," Cynthia repeated, "Disintegrate it, burn it, vaporize it, pulverize it, smash it, tear it apart –– anything. Just destroy it. A robot like that should not exist."

"But –– but we don't know who programmed it! The culprit behind all this! The one who––"

"Jessop. Bellamy Jessop, ex-roboticist at IRC. He is the one who made that robot. He is the one behind all this."

"But, how do you know?"

"The robot. It spoke his name. It called him 'master'. Well, isn't that fairly obvious?"

"'Master'?" Rinnard spoke, "Cynthia, what did happen inside there? How did you disable that robot? You've not told us anything!"

"It was pretty easy," she replied, "All I did was present the robot with an insoluble problem. After I entered the bus, I straightaway ordered the robot to bow down before me."

"You did what?"

Cynthia raised a hand. "Please, let me finish. You men are such impatient creatures! As I said, I ordered it to bow down before me. It refused, proving my theory that it had been ordered strictly not to obey any command of any other human being and carry out its mission at all cost." She smiled. "To carry out its mission at all cost. That was the green signal for me. With its First Law removed, the top priority is automatically shifted to the Second Law and then the Third Law. The Second Law becomes: 'A robot must obey the orders given it by human beings.' And the Third Law becomes: 'A robot must protect its own existence as long as such protection does not conflict with the Second Law.'

"And so, I presented the robot with a little problem. I told it that if it took the ransom money and got out of the bus, it would immediately be destroyed – something which would mean the violation of both the Second Law for failing its mission, as well as the Third Law for being destroyed. A lie, for the bullets would scarcely damage it, so heavily armored it was. But being a dumb robot as it was, the thought probably never occurred to it.

"I also told it that if it surrendered (which it was unlikely to do) and did not take the money, then it would still be violating the Second Law by not fulfilling its mission. Either way, it would violate the Second Law. If it had been a newer model, like the LR8 (successor to the NR8), then it would not have been fooled by my first argument. But, thankfully for us and the passengers and unfortunately for Bellamy, its intelligence was low. All it was concerned with was trying to find a way out of the problem I'd given it. When it couldn't, it broke down. And before it totally broke down and asked it the name of its master. It spoke of Jessop and broke down."

At this point, Cynthia paused and took a long breath before continuing with an air of victory.

"There is only one roboticist whose names is Jessop: Dr. Bellamy Jessop of the International Robots Corporation, who was stripped of his title and job little more than four years ago and spent two years in jail for stealing robot technology and using them to illegally construct robots in his own home. Apparently, he did not stop."

Cynthia turned around, adjusted her shoe and headed for the door. "I'll be heading back to my office. Oh, and next time a case like this pops up, and I hope it doesn't, just use your head. Nature didn't give you a brain for wasting it."

{This is my first story set in the Robot universe created by Isaac Asimov. I would welcome reviews. Thanks.}