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."

Bigman looked at him doubtfully. "Listen, you're try- ing to sell me a bale of space dust." He turned abruptly and moved away. "I think I'll look at the book after all."

The Hilda moved on and took a new position, while the microwaves shot out, searching and searching. Then again it moved. And again. Slowly Lucky was screening the underwater plateau on which the city of Aphrodite stood.

He waited grimly at the instruments. Somewhere down here his friend Lou Evans must be. Evans's ship could navigate neither air nor space, nor any ocean depth of more than two miles, so he must be confined to the relatively shallow waters of the Aphrodite plateau.

The first answering flash caught his eye even as he repeated the must to himself for the second time. The microwave feedback froze the direction finder in place, and the return pip was brightening the entire receiving field.

Bigman's hand was on Lucky's shoulder instantly. "That's it! That's it!"

"Maybe," said Lucky. "And maybe it's some other ship, or maybe it's only a wreck."

"Get its position, Lucky. Sands of Mars, get its position!"

"I'm doing it, boy, and we're moving."

Bigman could feel the acceleration, hear the churning of the propeller.

Lucky leaned closely over the radio transmitter and its unscrambler, and his voice was urgent. "Lou! Lou Evans! Lucky Starr at this end! Acknowledge signals! Lou! Lou Evans!"

Over and over again, the words pushed out along the ether. The returning microwave pip grew brighter as the distance between the two ships grew less.

No answer.

Bigman said, "That ship we're pipping isn't moving, Lucky. Maybe it is a wreck. If it were the councilman, he'd either answer or try to get away from us, wouldn't he?"

"Sh!" said Lucky. His words were quiet and urgent as he spoke into the transmitter: "Lou! There's no point in trying to hide. I know the truth. I know why you sent the message to Earth in Morriss's name asking for your own recall. And I know who you think the enemy is. Lou Evans! Acknowledge..."

The receiver crackled, static-ridden. Sounds came through the unscrambler and turned into intelligible words: "Stay away. If you know that, stay away!"

Lucky grinned his relief. Bigman whooped.

"You've got him," shouted the little Martian.

"We're coming in to get you," said Lucky into the transmitter. "Hold on. We'll lick it, you and I."

Words came back slowly, "You don't-understand-

- I'm trying to..." Then, almost in a shriek, "For

Earth's sake, Lucky, stay away! Don't get any closer!"

No more came through. The Hilda bored toward the position of Evans's ship relentlessly. Lucky leaned back, frowning. He murmured, "If he's that afraid, why doesn't he run?"

Bigman didn't hear. He was saying jubilantly, "Terrific, Lucky. That was terrific the way you bluffed him into talking."

"I wasn't bluffing, Bigman," said Lucky, grimly. "I know the key fact involved in this whole mess. So would you, if you stopped to think about it."

Bigman said shakily, "What are you getting at?"

"Do you remember when Dr. Morriss and you and I entered the small room to wait for Lou Evans to be brought to us? Do you remember the first thing that happened?"

"No."

"You started laughing. You said I looked queer and deformed without a mustache. And I felt exactly the same way about you. I said so. Remember?"

"Oh, sure. I remember."

"Did it occur to you to wonder why that was? We'd been watching men with mustaches for hours. Why was it that the thought suddenly occurred to both of us at that particular time?"

"I don't know." "Suppose the thought had occurred to someone else who had telepathic powers. Suppose the sensation of surprise flooded from his mind to ours."

"You mean the mentalist, or one of them, was in the room with us?"

"Wouldn't that explain it?"

"But it's impossible. Dr. Morriss was the only other man...Lucky! You don't mean Dr. Morriss!"

"Morriss had been staring at us for hours. Why should he be suddenly amazed at our not having mustaches?"

"Well, then, was someone hiding?"

"Not hiding," said Lucky. "There was one other living creature in the room, and it was in plain view."

"No," cried Bigman. "Oh, no." He burst into laughter. "Sands of Mars, you can't mean the V-frog?"

"Why not?" said Lucky calmly. "We're probably the first men without mustaches it ever saw. It was surprised."

"But it's impossible."

"Is it? They're all over the city. People collect them, feed them, love them. Now do they really love V-frogs? Or do the V-frogs inspire love by mental control so as to get themselves fed and taken care of?"

"Space, Lucky!" said Bigman. "There's nothing surprising about people liking them. They're cute. People don't have to be hypnotized into thinking that."

"Did you like them spontaneously, Bigman? Nothing made you?"

"I'm sure nothing made me like them. I just liked them."

"You just liked them? Two minutes after you saw your first V-frog, you fed it. Remember that?"

"Nothing wrong with that, is there?"

"Ah, but what did you feed it?"

"What it liked. Peas dipped in axle g..." The little

fellow's voice faded out.

"Exactly. That grease swelled like axle grease. There was no mistaking what it was. How did you come to dip the pea in it? Do you always feed axle grease to pet animals? Did you ever know any animal that ate axle grease?"

"Sands of Mars!" said Bigman weakly.

"Isn't it obvious that the V-frog wanted some, and that since you were handy it maneuvered you into delivering some-that you weren't quite your own master?"

Bigman muttered, "I never guessed. But it's so clear when you explain it. I feel terrible."

"Why?"

"It's a hateful thing, having an animal's thoughts rolling around inside your head. It seems unsanitary." His puckish little face screwed up in an expression of revulsion.

Lucky said, "Unfortunately, it's worse then unsanitary."

He turned back to the instruments.

The interval between pip and return disclosed the distance between the two ships to be less than half a mile when, with surprising suddenness, the radar screen showed, unmistakably, the shadow of Evans's ship.

Lucky's voice went out over the transmitter. "Evans, you're in sight now. Can you move? Is your ship disabled?"

The answer came back clearly in a voice torn with emotion. "Earth help me, Lucky, I did my best to warn you. You're trapped! Trapped as I'm trapped."

And as though to punctuate the councilman's wail, a blast of force struck the subship Hilda, knocking it to one side and jarring its main motors out of commission!