arm
of
the
law

It was a big, coffin-shaped plywood box that looked like it weighed a ton. This brawny type just dumped it through the door of the police station and started away. I looked up from the blotter and shouted at the trucker's vanishing back.

"What the hell is that?"

"How should I know?" he said as he swung up into the cab. "I just deliver, I don't X-ray 'em. It came on the morning rocket from earth is all I know." He gunned the truck more than he had to and threw up a billowing cloud of red dust.

"Jokers," I growled to myself. "Mars is full of jokers."

When I went over to look at the box I could feel the dust grate between my teeth. Chief Craig must have heard the racket because he came out of his office and helped me stand and look at the box.

"Think it's a bomb?" he asked in a bored voice.

"Why would anyone bother—particularly with a thing this size? And all the way from earth."

He nodded agreement and walked around to look at the other end. There was no sender's address anywhere on the outside. Finally we had to dig out the crowbar and I went to work on the top. After some prying it pulled free and fell off.

That was when we had our first look at Ned. We all would have been a lot happier if it had been our last look as well. If we had just put the lid back on and shipped the thing back to earth! I know now what they mean about Pandora's Box.

But we just stood there and stared like a couple of rubes. Ned lay motionless and stared back at us.

"A robot!" the Chief said.

"Very observant; it's easy to see you went to the police academy."

"Ha ha! Now find out what he's doing here."

I hadn't gone to the academy, but this was no handicap to my finding the letter. It was sticking up out of a thick book in a pocket in the box. The Chief took the letter and read it with little enthusiasm.

"Well, well! United Robotics have the brainstorm that ... robots, correctly used will tend to prove invaluable in police work ... they want us to co-operate in a field test ... robot enclosed is the latest experimental model; valued at 120,000 credits."

We both looked back at the robot, sharing the wish that the credits had been in the box instead of it. The Chief frowned and moved his lips through the rest of the letter. I wondered how we got the robot out of its plywood coffin.

Experimental model or not, this was a nice-looking hunk of machinery. A uniform navy-blue all over, though the outlet cases, hooks and such were a metallic gold. Someone had gone to a lot of trouble to get that effect. This was as close as a robot could look to a cop in uniform, without being a joke. All that seemed to be missing was the badge and gun.

Then I noticed the tiny glow of light in the robot's eye lenses. It had never occurred to me before that the thing might be turned on. There was nothing to lose by finding out.

"Get out of that box," I said.

The robot came up smooth and fast as a rocket, landing two feet in front of me and whipping out a snappy salute.

"Police Experimental Robot, serial number XPO-456-934B, reporting for duty, sir."

His voice quivered with alertness and I could almost hear the humming of those taut cable muscles. He may have had a