Technology

The body is Rottweiler-sized, segmented into overlapping hard plates like those of a rhinoceros. The legs are long, curled way up to deliver power, like a cheetah's. It must be the tail that makes people refer to it as a Rat Thing, because that's the only ratlike part - incredibly long and flexible.

The grass under the Rat Thing is beginning to smoke.

"Careful. Supposedly they have really nasty isotopes inside," Hiro says behind her... "A radioactive substance that makes heat. That's its energy source."

"How do you turn it off?"

"You don't. It keeps making heat until it melts."

The body converges to a sharp nose. In the front it bends down sharply, and there is a black canopy, raked sharply like the windshield of a fighter plane. If the Rat Thing has eyes, this is where it looks out.

As part of Mr. Lee's good neighbor policy, all Rat Things are programmed never to break the sound barrier in a populated area. But Fido's in too much of a hurry to worry about the good neighbor policy. Jack the sound barrier. Bring the noise.