"To the roof!" he ordered.

By the time the five minutes of grace were up everybody was on the flat roof of the temple. The moon was just rising. It looked like a gigantic conflagration on the horizon.

"Time is up!" Voronoff yelled, from some place of concealment. "What did you decide."

"We decided you could go to h.e.l.l!" Craig answered. "If you want us, you've got to come and get us."

Hiding around the temple thousands of the Ogrum could be vaguely glimpsed. Captain Higgins surveyed the scene. "We command all approaches to the building," he said. "If they try to charge us, it will be slaughter. We've still got a chance, Craig."

"You're d.a.m.ned right we have!" the big man answered.

"Except," the captain continued thoughtfully, "for ammunition, food, and water, we're all right."

"If we're not out of here by the time our ammunition runs out, we'll never escape," Craig answered. "However, we'll be out of here in an hour."

"I hope you know what you're talking about," was Higgins' only comment.

The Ogrum were making no attempt to attack. Craig circled the roof of the temple, seeing that sub-machine guns covered all approaches. A wind, moving from the direction of the swamp, brought with it the sound of the dinosaurs. The scene was like a setting from some fantastic movie--a full moon burning like a huge fire on the horizon, incredible beasts screaming in the night, a group of embattled humans on the roof of a temple as old as time.

"We've got them!" Craig thought. "They can't get to us and they don't dare attack. If they wait an hour--"

In some hidden spot outside the temple something went _plunk_. The sound was not sharp enough to be called an explosion. It was a plunk, like a rock falling in a rain barrel.

A small round object arched slowly through the air and hit on the roof of the temple. It also went _plunk_. No explosion. Just a _plunk_. A cloud of white smoke puffed out.

"What the devil is that?" Craig thought uncertainly. "Are they throwing grenades at us? Was the first grenade a dud?"

He started toward the grenade. A whiff of the smoke stung his nostrils, sent a warning bell clattering wildly in his brain.

"Gas!" he yelled. "They're throwing gas grenades at us. Stay away from that smoke."

The Ogrum had attacked the Idaho with their sleeping gas! The guards in the temple had carried sacks of what Craig had thought were ordinary grenades. They had been gas grenades!

_Plunk_ went the projector outside the temple. _Plunk_ went the grenade that struck on the roof.

_Plunk, plunk, plunk_--A shower of grenades came over. Gas swirled over the roof of the temple.

"Knock out those projectors!" Craig shouted. He leaped to the wall of the temple, began firing. All around him other guns were letting go. Up to now it had been necessary to conserve ammunition as much as possible.

If the projectors were not knocked out, no amount of ammunition would do the humans any good.

The rattle of sub-machine guns was a continuous tumult of sound. Fires still burned in the city and the air was becoming heavy with smoke. All around the temple the Ogrum were lurking. They were not venturing into the open. Now and then they could be glimpsed darting from shelter to shelter.

_Plunk--plunk--plunk--_

More gas grenades. .h.i.t on the roof.

Somewhere near him Craig heard a man choke and gasp for breath.

Everywhere, even above the rattle of the machine guns, he could hear men coughing. Something stung his lungs and he coughed himself. The machine gun fire began to thin out as choking men dropped their guns. Craig found himself firing blindly, searching for the hidden projectors. The plunk of the gas grenades was loud in his ears.

"Tough luck," a thin voice said near him.

He looked around and saw Margy Sharp. The girl was holding a handkerchief over her nose and was trying to keep from breathing. She was swaying.

"I feel like I want to go to sleep," she whispered.

The gas was getting to her. It was getting to others, too. Many of the sailors had fallen. Some of them were trying to drag themselves back to the edge of the roof, trying to lift guns with hands that no longer had the strength for the task.

"We fought a good fight," Margy Sharp whispered. "Too bad we lost."

"We haven't lost yet," Craig gritted.

He was lying and he knew it. His only hope was phase four of the attack plan. Unless phase four went into operation within the s.p.a.ce of minutes, they were doomed. "What the h.e.l.l has happened to Michaelson?" he thought.

_Plunk, plunk, plunk_, went the grenades.

Had the scientist failed? Had something happened to Michaelson?

The night was hideous with the yells of the Ogrum. Sensing victory, they were screaming with delight. Meanwhile, all over the roof of the temple, more of the gas grenades were exploding. The wind, which had quickened to a stiff breeze, swept much of the gas away. But not all of it. One whiff of it and a man lost half his efficiency. Three whiffs and he was asleep.

A man in an officer's uniform crawled to Craig's feet, looked up at him.

It was Captain Higgins.

"I--I guess this is it," the captain said.

"I guess so," Craig said miserably. The gas stung his lungs again and he coughed. Slowly, a little at a time, he could feel a deadly la.s.situde stealing over him. A weight was tugging at his knees, trying to force his legs to buckle. More than anything else in the world, he wanted to lie down and go to sleep. He fought against the impulse. From this threatened sleep a man would awaken all right--in the prison pen of the Ogrum, there to wait his turn to become a sacrifice to the sun.

Two or three machine guns--no more--were still firing, holding off the Ogrum horde. When those guns stopped--

The flames of the burning city danced in the night. The air was heavy with smoke. The screams of the dinosaurs were louder, as if the great beasts were excited by the conflagration in the city of the Ogrum. Craig was vaguely aware that only two guns were firing. In spite of all his efforts to resist the impulse, he sank to his knees. The grenades continued to plunk on the roof. Only one gun was firing. Beside him, Craig saw that Margy Sharp had gone quietly to sleep. She looked like a little girl who is all tired out with play and has decided to lie down and take a nap.

_Boom-boom! Boom-boom-boom!_

Five thudding explosions came through the night. They did not come from the temple, or near it. They were at least half a mile away.

The sound lifted Craig to his feet.

"Michaelson!" he screamed. He tried to look in the direction from which the sound of the explosions had come. The smoke was too heavy. He could not see.

"Michaelson--" his voice was a whisper. "For G.o.d's sake, hurry!"

There was no answer. Craig waited. No more explosions came. He sank to his knees, fighting against the impulse to sleep. He was dimly aware that the screams of the Ogrum had died into abrupt silence. No more grenades were plunking on the roof. He wondered if the Ogrum were preparing to charge the temple, to strike down all who had strength left to oppose them. He lifted himself up, looked over the edge.

The Ogrum were no longer watching the temple. They were staring in the direction of the explosions. They had come out into the open. He could see little groups of them nervously looking in the other direction.