Lucky said, "Anything new on the man who started it all? The man at the lock?"

"He's under observation. A madman, obviously."

"Does he have a.record of mental imbalance?"

"Not at all. It was one of the things I checked into. As chief engineer, you know, the dome personnel are under me."

"I know. It's why I came here to you."

"Well, I wish I could help, but the man was just an ordinary employee. He's been on our rolls for some seven months and never gave any trouble before. In fact, he had an excellent record; quiet, unassuming, diligent."

"Only seven months?"

"That's right,"

"Is he an engineer?"

"He has a rating as engineer, but actually his work consisted largely of standing guard at the lock. After all, traffic passes in and out of the city. The lock must be opened and closed, bills of lading checked, records kept. There's a lot more to managing the dome than just engineering."

"Did he have any actual engineering experience?"

"Just an elementary college course. This was his first job. He's quite a young man."

Lucky nodded. He said casually, "I understand there have been a whole series of queer accidents in the city lately."

"Have there?" Turner's weary eyes stared at Lucky, and he shrugged. "I rarely get a chance to look at the news-etheric tapes."

The communo buzzed. Turner lifted it and held it to his ear for a moment. "It's for you, Starr."

Lucky nodded. "I left word I'd be here." He took the communo but did not bother to activate the screen or to raise the sound above the ear-contact stage. He said, "Starr at this end."

Then he put it down and stood up. "We'll be going now, Turner."

Turner rose, too. "All right. If I can help you in the future, call on'me any time."

"Thank you. Give our respects to your wife, will you?"

Outside the building Bigman said, "What's up?"

"Our ship is ready," said Lucky, flagging down a groundcar.

They got in, and again Bigman broke the silence. "Did you find out anything from Turner?"

"A thing or two," said Lucky curtly.

Bigman stirred uneasily and changed the subject. "I hope we find Evans."

"I hope so, too."

"Sands of Mars, he's in a spot. The more I think of it, the worse it seems. Guilty or not, it's rough having a request for removal on grounds of corruption sent in by a superior officer."

Lucky's head turned and he looked down at Bigman. "Morriss never sent any report on Evans to central headquarters. I thought you understood that from yesterday's conversation with him."

"He didn't?" said Bigman incredulously. "Then who did?"

"Great Galaxy!" said Lucky. "Surely it's obvious. Lou Evans sent that message himself, using Morriss's name."

Lucky handled the trim subsea craft with grow

ing expertness as he learned the touch of the controls and began to get the feel of the sea about them.

The men who had turned the ship over to them had worriedly suggested a course of instruction as to its management, but Lucky had smiled and confined himself to a few questions while Bigman exclaimed with Bigman-ian braggadocio, "There isn't anything that moves that Lucky and I can't handle." Braggadocio or not, it was very nearly true.

The ship, named the Hilda, drifted now with the engines cut off. It penetrated the inky blackness of the Venusian ocean with smooth ease. They were navigating blind. Not once had the ship's powerful beams been turned on. Radar, instead, plumbed the abyss ahead more delicately and more informatively than light possibly could.

Along with the radar pulses went the selected microwaves designed to attain maximum reflection from the metal alloy that formed the outer hull of a subship. Their range in the hundreds of miles, the microwaves plunged their probing ringers of energy this direction and that, seeking the particular design of metal that would send them careening back in their tracks.

So far, no reflecting message had come back, and the 72 Hilda settled down in the ooze, half a mile of water above it, and motionless except for a slow rocking with the mighty sway of Venus's globe-girdling oceanic currents.

For the first hour Bigman had been scarcely aware of the microwaves and the object of their search. He had been lost in the spectacle to be seen from the portholes.

Venusian subsea life is phosphorescent, and the black ocean depths were dotted with colored lights thicker than the stars in space, larger, brighter, and most of all, moving. Bigman squashed his nose against the thick glass and stared, fascinated.

Some of the life forms were little round splotches, whose movement was a slow ripple. Others were darting lines. Still others were sea ribbons of the type Lucky and Bigman had seen in the Green Room.

Lucky joined him after a while. He said, "If I remember my xenozoology…"

"Your what?"

"That's the study of extraterrestrial animals, Bigman. I've just been looking through a book on Venusian life. I left it on your bunk in case you want to look at it."

"Never mind. I'll take it second hand from you."

"All right. We can start with those little objects. I think that represents a school of buttons."

"Buttons?" said Bigman. Then, "Sure, I see what you mean."

There were a whole series of yellow ovals of light moving across the black field visible through the porthole. Each had black markings on it in the form of two short parallel lines. They moved in brief spurts, settled down for a few moments, then moved again. The dozens in view all moved and rested simultaneously, so that Bigman had the queerly swimming sensation that the buttons weren't moving at all, but that every half minute or so the ship itself lurched.

Lucky said, "They're laying eggs, I think." He was silent for a long moment, then said, "Most of these things I can't make out. Wait! That must be a scarlet patch there. See it? The dark red thing with the irregular outline? It feeds on buttons. Watch it."

There was a scurrying among the yellow blotches of light as they became aware of the swooping predator, but a dozen buttons were blotted out by the angry red of the scarlet patch. Then the patch was the only source of light in the porthole's field of vision. On all sides of it, buttons had scattered away.

"The patch is shaped like a large pancake turned down at the edge," said Lucky, "according to the book. It's hardly anything but skin with a small brain in the center. It's only an inch thick. You can tear it through and through in a dozen places without bothering it. See how irregular the one we're watching is? Arrowfish probably chewed it up a bit."

The scarlet patch moved now, drifting out of sight. There v/as little left where it had been except for one or two faint, dying glimmers of yellow. Little by little, buttons began moving back again.

Lucky said, "The scarlet patch just settles down to the bottom, holding on to the ooze with its edges and digesting and absorbing whatever it covers. There's another species called the orange patch which is a lot more aggressive. It can shoot a jet of water with enough force to stagger a man, even though it's only a foot wide and not much more than paper thin. The big ones are a lot worse."

"How big do they get?" asked Bigman.

"I haven't the slightest idea. The book says there are occasional reports of tremendous monsters-arrowfish a mile long, and patches that can cover Aphrodite City. No authentic cases, though."

"A mile long! I'll bet there aren't any authentic cases."

Lucky's eyebrows lifted. "It's not as impossible as all that. These things here are only shallow-water specimens. The Venusian ocean is up to ten miles deep in spots. There's room in it for a lot of things."