The freight-carrier had been in vacuum dock for nine Greenwich days. In twelve G-hours, it would depart, regardless of local law. It carried the wealth of worlds. It wasn't going to be delayed because a few tons of stolen actinium were hidden somewhere within its vast corpus.
So a Sherlock was downloaded into a welding robody, and his Watson into another. "This isn't going to be easy," the Watson observed when he saw the eighty-mile-long ship.
"Logic, old friend! Deductive reasoning can solve any problem," said the Sherlock. "We'll start by interviewing the crew."
But none of the robot crew had seen anything out of the ordinary. The ship had been serviced by the usual robot servitors, and though over a hundred human beings had come and gone (the carrier was equipped for human passengers but this was a freight run and completely robotic), they were all long-time employees of the Port Authority.
"An inside job, obviously," the Watson said.
"Indeed! And by a human."
"How do you know that?"
"Because robots don't commit crimes. Let us proceed to the human section of the ship. It is there we shall find the purloined actinium."
A few G-minutes later, they were floating through the unused human quarters. It was shaped like a sphere with the two poles lopped off. In flight, it was filled with oxygen and spun to provide artificial gravity. Small villages were dotted here and there about its surface.
"It could be anywhere," the Watson said, glumly surveying the cluttered surface. "We'll never find it in the time allotted us."
"Surely, we don't need to search everywhere! What do we know about actinium?"
"It's intensely radioactive. The average lifetime of an actinium atom is thirty-three years. That's why it has to be manufactured, and therefore why it's so valuable. If we had radiation detectors with us, it would be the easiest thing in the world to find it." The Watson let out an artificial sigh. "But we don't have radiation detectors and it would take a full G-day to have them shipped to us. And beyond that, we know nothing. We don't even know what it looks like."
"Watson, you've done it!" the Sherlock cried. He radioed a series of commands to the ship's autonomic systems. The airlocks began cycling shut.
"What are you doing?"
"Flooding the human quarters with oxygen, of course."
"What will that do?"
"You said it yourself. Actinium is intensely radioactive—so radioactive that it excites the air about it, and glows in the dark. We'll turn out the lights and it will reveal itself to us."
Not long after, the freight-carrier departed. The Sherlock and the Watson floated alongside the offloaded actinium waiting for a lighter to arrive and recover the stolen merchandise. "That was a cunning bit of reasoning on your part," the one robot said..
"Pshaw!" replied the Sherlock, pleased. "It was elementary, my dear Watson."
© 2003 by Michael Swanwick and SCIFI.COM.