"I'm walking east on 1990," he sub vocalised. "If I reach the corner of Second without making contact I'm going to assume the bandit is either near me or has got past me. Til wait thirty seconds then I'll say "off. As soon as I do that I want you to throw the switch and kill every image projector in the Street. That should take our visitor by surprise and give me a couple of seconds to pick him out."

"Okay, Carry" Mellor said, "but suppose there's more than one."

"It won't matter — Tin geared up to paralyse half the Street."

Tm with you."

"Be glad you aren't." Dallen moved tentatively along the block, grateful that fashions in men's casual clothing had varied little over the centuries. His tan jacket, slacks and open-necked shirt made a virtually timeless ensemble which enabled him to mingle unobtrusively with tourists and holomorphs alike. He kept to the outer edge of the sidewalk, trying to scan both sides of the Street at once. His task was made a little easier by the fact that he could remember some of its permanent, though insubstantial, residents. There was the newspaper seller at the entrance to the Clarence Hotel, the amiably tubby guard at the bank, the cigar store owner who grinned his idealised grin at passers-by. Figures who paused and spoke to them, obeying their programmes, were immediately identifiable as holomorphs, as were taxi drivers, delivery men and the tike.

Dallen's real problem lay with strolling window-shoppers and sightseers. A couple walking hand-in-hand with two smalt children were likely to be flesh-and-blood tourists, but similar family groups had been included in the Street's cast of holomorphs to establish a homely atmosphere — and there was nothing to stop bombers adopting the same camouflage. By the time he reached the midpoint in the block Dallen's palms were sweating and his heart rate had climbed until there was a continuous fluttering agitation in the centre of his chest.