A line of robots marched. A bird overhead, if there had been any birds left, would have seen a line of chrome and wire stretching from horizon to horizon. Their legs lifted their feet and placed them down again in perfect synchronization, all dictated by a cesium clock buried deep within the robots' citadel.
Now the line of robots marched towards the final human outpost, a ratty town made primarily of ragged tents and more ragged humans.
The robots at the back rolled off of the production line and began marching toward the human colony.
The robots at the front laid down rubber panels so that the metal feet of their comrades would have traction.
Each robot that wasn't building other robots or laying rubber had its arms replaced with oversize pneumatic shears extended, ready for pruning humans.
In the robots' citadel a pair of suicidal knuckleheads tumbled down a ventilation shaft towards the cesium clock. They represented the final hope of humanity. They also represented the effect of gravity and slick, sloped ventilation shafts.
Holly's ass hit the grill at the end of the duct and the metal bands bent, but didn't break.
When Sally hit Holly, however, the grill gave up and out they both spilled in a sweaty mess of jumbled human limbs.
"That hurt, buttass," Sally told Holly.
"You're the one that ran into me, you should be more careful." She picked herself up.
"I hadn't expected you to stop! Next time I'll try to be more mindful with my uncontrollable descent!"
After a few more moments of bickering, they took in the room. The architect only knew about one building material: smooth steel tiles. A grid of fluorescent bulbs in the ceiling illuminated the only object in the room, which neither Holly nor Sally identified immediately.
A few screens sat upon a large cabinet. Next to it sat a similarly-sized cabinet but stood upon one thick end. A web of cables connected the two. A small, ugly clock sat above it. Instead of showing the time, it showed a long string of numbers that constantly incremented.
"The cesium clock!" Sally yelled. She ran up and was about to begin pulling wires when one of the steel panels slid to the side. A robot came in with its human-cutting shears already clicking their blades together.
"I'll take care of it!" Holly bellowed, moving to distract the robot. The robot attempted to turn. Its feet, however, provided no traction as no rubber mats had been laid on the floor. It clattered to the floor and began to flop around.
"That was anti-climactic." Sally pulled a fistful of wires from one of the cabinets. The clock stopped incrementing.
"HUMAN FOOL. THAT IS A HYDROGEN BOMB. WHENEVER A WIRE IS REMOVED IT IS ARMED. DO YOU THINK THAT WE WOULD LET THE HUMANS FIND OUR CONTROL CLOCK?"
Holly looked through the doorway that was revealed when the robot entered. A set of glowing digits sat on a table in the other room.
"Is that your control clock?"
"YES, BUT IS TOO LATE. THIS BOMB WILL EXPLODE AND VAPORIZE ALL OF US IN LESS THAN TEN SECONDS. NINE. EIGHT."
"Won't it also vaporize your control clock? I mean, we're pretty close. I could probably wing this broken vent grate and hit it."
"NO THAT IS A BOMB-PROOF CLOCK."
"No way. Wait. Maybe you were built with a fail safe. You were engineered with a fundamental inability to secure your control clock properly. Why else would an otherwise unstoppable army of robots put an explosive death trap so close to the death trap that if you spilled a glass of water it would short out both of them?"
"MY PROGRAMMING SAYS THAT YOU'RE WRONG, BUT THAT DOESN'T REALLY MAKE SENSE. I HAVE TWO SECONDS TO PONDER THAT INCONSISTENCY BEFORE WE ARE BLOWN INTO WISPS OF PLASMA BUT TO A ROBOT THAT IS A HELLISHLY LONG TIME. ONE."
Holly had thrown the broken grate from the ventilation shaft like a boomerang. The piece of metal scythed towards its target and its jagged arms revolved through the air like a ripsaw. Metal met wire as it chewed through the nervous system of the clock.
The digits on its face dissolved.
Holly and Sally exhaled. They were thrilled to discover that their phase hadn't been traumatically altered.
"I IMAGINE THAT WILL HAVE SERIOUS CONSEQUENCES FOR ROBOTS EVERYWHERE. BUT FOR RIGHT NOW I AM EXPERIENCING WAVES OF GLEEFULNESS. I AM SO GLEEFUL THAT I THINK THAT I SHALL LAY HERE IN BLISSFUL REPOSE RATHER THAN CHASING YOU FROM THE ROOM WHILE WAVING MY HUMAN-CUTTING SHEARS AT YOU."
"We appreciate that," Holly said.
The Moral: a hydrogen bomb makes a great home security system because no thief will bother with a flaming bundle of radioactive toothpicks.