"Darling," she said rather lamely. "I think that fatigue is about to get the better of us."

"Think again," Ed said.

"I guess you're right," she answered. "Even without vitaplasm, it's not much of a stunt to give a guided missile or a spy-robot the form of a little bird, with television eyes. And a Midas Touch weapon, or something equally unpleasant, built into it. At the hotel in Port Smitty, it was unrecognizable among the other caged canaries. Here, though, it's unmistakably identified. Which means that whoever is guiding it—the police looking for your Uncle Mitch or friends of Granger's, or whoever else—don't care any more that we know what it is. We're helpless now—they think."

A dull fury came to Ed Dukas. He might have guessed that all chances of their eluding surveillance would have been countered carefully. This birdlike mechanism must have followed them all the way from Port Smitty, keeping just out of sight.

Then a more hopeful idea hit him. But reason conquered it. "No," he said aloud, gripping Barbara's shoulder so that she could hear. "If the pseudo-canary was Uncle Mitch's guide for us, it would have revealed itself sooner, and the messages on paper would not have been necessary."

In a flash Ed drew his own Midas Touch and fired it at the place among the broken rocks where the canary had just vanished. At a little distance there was the usual spurt of incandescence, fringed now with red dust. But from the projecting boulders near its base, a small yellow form spurted with a faint and musical twitter of mockery. Then a heavy voice spoke—one which neither Ed nor Barbara recognized just then:

"Better luck next time, robot lovers. Lead on!"

Thereafter, the false canary was careful not to show itself. And Ed was left with his frustrated anger, and with other uncertain thoughts. What if the written messages had not come from Mitchell Prell at all, but from someone else with an unknown purpose? Or, what if they were from Uncle Mitch, but had been prepared long ago and left to be presented to him, Ed Dukas, by means of some mechanical agent? What if—well—many things.

Using his tiny portable radar unit to locate the bird drew only a blank. Perhaps the little mechanism with a radio speaker for a voice was effectively shielded against such detection, even at short range.

To attempt evasive action would be a waste of time and waning energy. There was nothing to do but go on, see what developed, and trust to luck. There was the certainty that real pursuit would come, but what shape it would take remained unknown.