They went east for six days before turning south again, during which the realness and solidity of the seascape hallucinations waxed and waned irregularly. Occasionally, they would fade so much that they almost disappeared altogether, but a mile or two further on they would return to full force, suggesting that either the Ghost Ocean did indeed get stronger and weaker over time, as Jerry had suggested, or that it had a highly irregular outline. It did not get stronger than it had been when they'd decided to take the detour, however, until two weeks afterwards. Then, the illusion suddenly became so strong that reality disappeared altogether, and for the first time they actually began to feel the illusory water all around them.

"It's getting difficult to breathe!" gasped Thomas, as he struggled to breathe the air that he knew was all around him and ignore the imaginary weight of twenty feet of water pressing on his chest. Matthew was holding his breath, fearing he would drown if he took a breath, and Petronax was desperately trying to swim up to the surface, so close overhead.

"It's not real!" cried Jerry, who was also having difficulty breathing. With every breath he took, he feared his lungs would fill with water, drowning him. "It's not real! It's just an illusion! There's no water!"

Matthew was growing desperate. He was still holding his breath and struggling like a madman to swim through the water that he knew was all around him. He fell out of his saddle and flailed around on the grass, waving his arms and legs in wild swimming motions while his face turned purple. He knew that if he tried to take a breath, he would drown, and his belief would kill him. Petronax and Lirenna were suffering similarly, and the others, just barely able to keep a grip on reality, jumped down off their horses to help, although what they could do for them they had no idea.

Thomas shook Lirenna savagely by the shoulders and screamed at her to fight the illusion, all the while trying to ignore the sensation of water flooding down his windpipe and filling his lungs. "It's not real!" he shouted, as much to himself as to her, while her eyes stared in panic and she clamped her hand tightly over her nose and mouth. Thomas tried to pull her hand away, but stopped when he realised that if he forced her to take a breath while believing the illusion, she would die believing she was drowning. On the other hand, she would pass out from asphyxiation if she didn't start breathing soon. Would the illusion still kill her if she was unconscious? he wondered, thinking he could maybe knock her out. Yes, it would, he decided. He remembered the skeletons they had passed, and knew that losing consciousness would be no escape. The only way to help her was to help her disbelieve the illusion.

He locked eyes with her. "Lenny, you know this isn't real, you know it! Look at me! You can hear me talking to you, but how could I talk if we were underwater? You keep trying to swim, but you can't because you can't swim through empty air! Think about it! Trust me! Trust me, Lenny! You know I wouldn't lie to you!"

The panic faded from Lirenna's eyes and sanity returned. Gingerly, she took her hand away from her face, keeping her eyes fixed on Thomas's, who kept on giving logical, reassuring reasons why the water wasn't real. She took a shallow breath and felt cold, salty water filling her lungs. For a moment she began to panic again, but with a heroic effort of will she managed to remain in control of herself and ignore the illusion. She took a deeper breath, and finally managed to break the illusion's grip on her. Suddenly she was gasping madly for air, and Thomas felt a great surge of joy and relief. He hugged her tightly until she was fully recovered and able to stand once more.

Matthew and Petronax weren't faring nearly as well, though. Whereas the three wizards were familiar with illusions, having seen and experienced many of them at the University, and Drake and Diana had their rock steady faiths to cling to, the three fighting men were almost totally unfamiliar with them and so were especially vulnerable. Shaun and Matthew had seen Jerry's illusions several times, it was true, and had encountered several on the island of the Emerald Oracle, but none of them came even close to the one they were experiencing now.

Thomas later advanced the theory that Shaun's magic sword may have helped him to resist the illusion, since two magics in the same area sometimes interfered with each other, but Matthew and Petronax didn't have this advantage. It had been two or three minutes since either of them had taken a breath, and their deaths could only be seconds away now.

Shaun and Diana knelt next to Matthew, desperately trying the same thing that Thomas had tried with Lirenna, but with no success, and Drake was ordering Petronax to fight the illusion in the name of Samnos, equally unsuccessfully. Shaun looked up at Jerry, who was standing a few feet away, tugging at his short silvery beard with both hands and looking as if he was close to tears. "Do something!" begged the woodsman. "You're supposed to be the expert on illusions! Do something!"

But what can I do? thought Jerry helplessly. He looked at Matthew and Petronax, dying right before his eyes, and knew he was right. He had to do something! But what? All he could do was create more illusions, and pitifully primitive ones compared to the Ghost Ocean, but maybe one illusion could be used to fight another. If he could just make this ocean seem a little less realistic...

He pulled a scrap of wool from an inside pocket, said the magic words and concentrated on the effect he wanted to produce. Immediately, a circle of flames sprang into being around the two fighters. Soundless flames that produced no heat, it's true, but they converged around Matthew and Petronax, surrounding them and setting fire to their clothing. Seeing the flames apparently burning underwater, while their friends kept yelling at them that the ocean wasn't real, helped to put a little doubt into their minds, but it still took nearly a full minute longer before the hallucination reluctantly released its hold on them, leaving them gasping for breath in the grass like landed fish.

Jerry let the illusory flames die with relief. It wasn't until the illusion spell was completely ended that he realised how hard he'd been concentrating on it, forcing it to be as realistic as possible, and as a result his head ached so badly that it felt as though a stone giant was driving him into the ground like a nail with its fists. He hardly had time to think about it, however, before he was grabbed by a kneeling Diana and given a bonecrushing hug while she babbled tearful words of gratitude into his pointed ears. The others laughed when they saw his face turn beetroot red with embarrassment, such open displays of affection being totally against their nature.

"I'd like to second that," said Matthew when the cleric finally released him. "I'd be dead now if it weren't for you. We'll never ignore your advice again, I promise. From now on, wherever illusions are concerned, your word is law."

"You have my thanks as well," added Petronax, "and also my apologies." He spoke to all of them. "It was my insistence that we take the shortest route that almost got us all killed. From now on, I'll follow your lead in all things, since you're obviously much more experienced in travelling abroad than I am."

"It wasn't entirely your fault," said Drake. "I also wanted to take the quickest route, but I've learned that it's better to take a long, safe route than never get there at all. I'm beginning to think we should have gone back to Calmany after all."

"No," said Shaun. "That would have been safe enough, all right, but we would have lost too much time. We have to make a compromise between safety and speed. Now that we've all beaten the hallucination, I think we'll be all right from now on, provided we don't go any deeper in. What do you think, Matt? Will you be all right now?"

Matthew was still looking rather green and unsure of himself, but he nodded. The hallucination was still as strong as ever, and he had to keep fighting the sensation that he was breathing water, but he thought he could handle it now, so long as it didn't get any worse. "Yes, I'm fine now," he said, with another grateful look at Jerry.

"What about you, Lenny?" asked Shaun.

"I'm fine now," she said, hanging onto Thomas's arm. "It just took me by surprise, that's all. I had no idea that an illusion could be so realistic."

"Good. Well, in that case, if we're to carry on, I suggest that we do so. We don't know how far ahead of us the enemy is, and we can only hope that they've also been delayed, but the less time we lose now the better."

"I agree," said Drake. "If we're ready, let's go."

☆☆☆

The total realism and believability of the watery hallucination persisted for several more miles, but now that they had all defeated it once, they were able to cope with it, and even get used to it, to the extent that Thomas was able to resume his study of the illusory sea life. Over the following days, he catalogued hundreds of different species of quasi-fish and pseudo-crustaceans, jotting down brief descriptions and notes on their lifestyles and habitats, intending to write it all up as a book one day. He was particularly interested in a large, wide creature, well over forty feet long and thirty feet wide but only about two or three feet between its top and bottom surfaces, that swam slowly and serenely along the surface above them, blocking out the sun and casting a dark shadow over them as it filtered plankton out of the water with its gaping wide mouth. "Look!" he cried excitedly. "What does that remind you of?"

"Yeah," said Matthew, equally excited. "If it was a few hundred times larger and a bit flatter, it'd be the splitting image of the island fish we found a few months ago."

"It must be one of the young ones," said Diana. "I wonder how long they take to grow up?"

"Not necessarily," said Thomas. "It could be the evolutionary ancestor of the island fish. In fact, that's more likely, for two reasons. Firstly, if the island fish had existed two million years ago, there'd be fossils of them on the great plains that were once underwater, and none have ever been found. Secondly, such large creatures would be unlikely to have survived the war that ravaged the planet about then. Small creatures make much better survivors than large ones."

"We'll probably never know," said Drake as the illusory plankton feeder swam away. They watched it until the green water hid it from view, and then continued on.

They were past the worst now, and over the next couple of days the hallucinations slowly became less real, allowing reality to become visible once again. The Ghost Ocean still had one surprise left in store for them, however, and on the eighteenth day after entering the haunted land they saw a line of low hills ahead and to the right. "Look!" said Thomas, pointing. "If we go up onto those hills, we'll be able to see the ocean from above. It's only a little out of our way. What do you say?"

"We're on an important mission, vital to the safety of the world, not a holiday outing," said Petronax a little impatiently. "We haven't got time for sight seeing detours. You can come back later to explore, if you want, but right now we're in a hurry."

"Actually, it might be a good idea to climb those hills," said Drake unexpectedly. "From up there, we'd be able to get a good look at the surrounding land, and we might see something important. A ranger I knew a few months ago told me never to miss the opportunity for a good look around."

And so, to Thomas's delight, they struck off towards the hills, and a few hours later they were standing on the crown of the nearest. They were indeed above the level of the hallucinatory ocean, and could see it stretching to the horizon in all directions, the waves shining in the light of the solitary sun. Here and there, the long neck of some sort of aquatic reptile broke the surface to look around for a few moments before submerging again (how come we didn't see any of them underwater? thought Thomas in puzzlement), and in the air above them leathery winged batlike creatures flew in lazy circles, screeching like seagulls.

The hills must have been islands in that long distant time, because they were fringed by sandy beaches on which all kinds of sea debris lay along the high tide line. Shells similar to the ones they'd already seen on the sea bed, long strands of seaweed and the occasional dead pseudo-fish, its four eyes staring glassily up at them. Further up, land vegetation grew. Low shrubs just a little way up from the beach, building up to a small forest right on top. Like the sea life they had already seen, though, they were completely different from what they were used to. Apart from the different shapes and forms in which it grew, the most striking and obvious difference was the colour. Every plant was a bright, livid purple, from the smallest seedling to the tallest tree. There wasn't a single scrap of green anywhere.

"Purple plants," said Thomas in fascination. "Today, they're just tiny weeds that farmers hoe out of their fields. So they once grew to the size of trees, did they? Who would have believed it."

"There must be, I mean, must have been, green plants somewhere, though," said Drake thoughtfully. "Possibly living as weeds among the dominant purple plants in the same way that purple plants survive as weeds among green plants now. Their roles must have reversed following the war."

"Aren't purple plants poisonous?" asked Diana, remembering the times her mentor, Father Bryon, had had to cure cases of poisoning caused by tiny, purple leaves accidentally getting mixed up with a farmer's crops.

"Yes, all of them, without exception," agreed Thomas. "Some more so than others. Some of them you can eat until you're so full you feel sick and they'll give you no more than a bad headache, while others contain enough poison in one tiny leaf to kill a dozen people, but they're all poisonous to one extent or other. Not only that, but the flesh of those few creatures that can eat them is also poisonous, although not the other way round. They can eat us as much as they want. They can also eat green plants as well, those that eat plants that is."

"This is all very interesting," said Petronax, "but we're wasting time here. If you've finished looking around, I suggest we get a move on. The enemy won't be sitting around waiting for us."

"Yes, we're finished here," agreed Drake. "Let's go."

They took one last look at the illusory scene, the memory of a world that had passed away long before the coming of any of the races of humanity, before descending the other side of the hill and continuing south.