y. "But Colonel, surely you can tell us more."

Halsey tossed his cigarette away. "I will tell you as much as I think
best. These Martians, Molo and his sister, do not know of Venza; at
least, I think that they do not. They apparently have not been here
very long. How they got here, we don't know. There was no passenger or
freight ship. In Ferrok-Shahn, they have a dubious reputation at best;
but I won't go into that.

"Venza, I will show you these Martians and the rest depends upon you.
There is a mystery; you will find out what it is."

He reached for his inter-office audiphone. "I want to locate the
Martian _Set_ Molo. Francis, Staff X2, has it in charge."

The audible connection came in a moment. "Francis?"

We could hear the answering microphonic voice, "Yes Colonel."

"Is the fellow in a public place by any chance?"

"In the Red Spark Cafe, Colonel. With his sister and a party."

"Good enough. The Red Spark has an image-finder. Have you visual
connection?"

"Yes, the whole room; they have a dozen finders."

"Use a magnifier. Get me the closest view you can."

"It's done, Colonel. I did it just in case you called."

"Connect it."

In a moment our mirror-grid was glowing with the two-foot square image
of the interior of the Red Spark Cafe. I knew the place by reputation:
a fashionable, more or less disreputable eating, drinking and dancing
restaurant, where money and alcholite flowed freely. The patrons were
successful criminals of the three worlds, intermingled with thrilled,
respectable tourists who hoped they would see something really evil.

The Red Spark was not far from Halsey's office; it was perched high in
a break of the city roof, almost directly over Park-Circle 29.

"There he is," said Halsey.

We crowded around his desk. The image showed the interior of a large
oval room, balconied and terraced; a dais dance-floor, raised high in
the center with three professional couples gyrating there; and beneath
them the public dance-grid, slowly rotating on its central axis. A
hundred or so couples were dancing. The lower floor was crowded with
dining tables; others were upon the little catwalk balconies, and
still others in the terraced nooks and side niches, half-enshrouded,
half-revealed by colored draperies.

The image now was silent, for Halsey was not bothering with audio
connection. But it was a riot of color, flashing colored floodlights
bathing the dancers in vivid tints; and there were