the spaceship slid up orbit, overtaking the shining ovoid from which antennae sprouted like pins from a pin-cushion. the captured g-boat was lashed to the spaceship's side.

"you'd think they'd have some defenses, anyhow," grumbled tyruss, watching the ovoid on the screen.

"why?" countered jonner. "they knew we didn't have any g-boats left, and they didn't know we had any spaceships left, either. of course, they don't know this is our target, but i'll bet they have some ships from phobos on the way here now, anyhow."

their timing was just right. thirty minutes later the egg would swing around the limb of mars, in line of sight with marsport. but so far there had been no chance for the egg to receive a radio warning of the stolen g-boat.

the spaceship pulled abreast of the egg and jonner and tyruss went across to it in spacesuits. they passed through the airlock to find the egg's crew of three waiting with welcoming smiles. the smiles faded at the sight of their levelled heat-guns.

"sorry you weren't expecting us," said jonner, opening the face-plate of his spacesuit with his left hand. "you'll have to get into spacesuits."

they sent their captives through the airlock and across the intervening space to the spaceship, where the others would be awaiting them. then jonner and tyruss searched the egg for other marscorp personnel. they found none.

"we'd better get a line on her and get under way before those ships from phobos can get here," said tyruss.

"right," agreed jonner, and they got busy.

a towline secured between the two vessels, jonner and tyruss returned to the spaceship. the three marscorp captives had been secured by chains to stanchions on the storage deck, just above the engine deck. stein and farlan, the engineers, were standing by.

"we're getting under way," tyruss told them.

stein and farlan descended to the engine deck, and tyruss and jonner climbed to the control deck. on the centerdeck, aron and wessfeld, the astrogators, were asleep.

tyruss climbed into the control chair and switched the radio to the marscorp band. a voice blared from the communicator:

"marscorp calling the egg. marscorp calling the egg. come in, egg. can you hear us, egg? rebels captured g-boat here. double alert. marscorp calling...."

tyruss switched it off, laughing.

"a little late," he commented.

"yes," said jonner. "keep the receiver on that band, tyruss, because we won't be hearing from our side. but, until we finish our mission, i'm going to disconnect the sending equipment."

jonner floated to the other side of the control deck and moved around behind the control board. he was busy disconnecting wires, a few minutes later, when he heard an exclamation from tyruss.

he peeked around the edge of the control board. the three marscorp captives were floating up the companionway from below, heat-guns in their hands!

"keep your hands off those controls, reb," warned one of them. "this ship's staying right here."

"wasn't there another one in this gang, robbo?" asked another.

tyruss twisted in his chair and reached for his heat-gun. one of the marscorp men rayed him through the throat.

cautiously, jonner poked the muzzle of his heat-gun around the edge of the control board. methodically, he shot the three marscorp men, one by one. they died without discovering the source of the invisible heat-beam that cut them down.

tyruss was dead. cursing, jonner went below, heat-gun in hand. on the centerdeck, wessfeld's body floated. wessfeld was dead, burned through the chest. aron was not there.

he found all three of the others, locked in the airlock, without spacesuits. jonner watched aron suspiciously as they emerged.

"what happened?" he demanded of aron.

"i don't know," disclaimed aron. "they woke us up. they had heat-guns then. wessfeld tried to reach his, and they shot him. stein and farlan were already in the airlock when they brought me down."

"stein, were you and farlan constantly in sight of each other, as ordered?" asked jonner, watching aron. did aron's eyes widen apprehensively?

stein started.

"why, no," he admitted. "farlan was on the engine deck, and i was down in the airlock checking the spacesuits before blast-off. that's routine, you know. they herded farlan down and caught me by surprise."

"that's right," said farlan. "i was checking the engines when they came through the hatch from above with heat-guns."

"damn!" exploded jonner. "i gave everyone strict orders—all right, it's too late now. it just cost us two men, and one of the four of us left is a marscorp spy. everyone get above and strap down for acceleration."

the spy was aron or farlan, but he still didn't know which. aron could have feigned sleep, and slipped down to the storage deck to release and arm the marscorp men. or farlan could have climbed from the engine deck and done it while stein was in the airlock. whoever it was, he had chosen to be locked in with the others—probably in case the sortie failed.

now they were two men short, and still he would have to pair off with aron and pair stein with farlan. they would have to go on twelve-hour duty shifts, with only four hours free time.

and to what purpose? as tyruss had suggested several times, why couldn't they have just blasted the egg out of space, if the purpose was to get rid of it? why go to all the trouble of shifting it to an earthward orbit? the earth would be nowhere near the intersection point when the egg reached earth's orbit, if that made any difference.

jonner had at last let the others know, as he should have before, that one of them was a spy. but he would not tell them, as he had told tyruss, that he had disconnected the radio transmitter. let the spy try to get in touch with marscorp now!