The shark that was coming right at her. A blue shark, she guessed, acting completely out of character.

She had two choices: stay perfectly still and hope the shark did a flyby, or do something to make it reconsider its current course. Preferring the latter, she reached down to her thigh and pulled out the rusty dive knife.

The shark was only meters away, resolute in its intent.

Peta held the knife with the handle facing away from her, blade pointing toward her. She pulled her arm close, holding the knife in tight.

There was a theory among divers that hitting a shark on the nose sharply made it back up. Especially, so the theory went, if it really didn’t have you in mind for dinner. If it did, the theory was probably useless.

A meter away the shark, a gray bullet now, rocketed right at her chest, its eyes expressionless black dots.

For a moment she thought her arm was moving too slowly to catch it, but the handle miraculously hit the shark directly on its piglike nostrils. If she survived, she’d be sure to tell the experts what they could do with their shark theories.

The creature didn’t stop. If anything, the handle acted like a jolt of energy. The blue shark rammed her hard, the force of it shoving her to the side and knocking her regulator from between her teeth. A giant bubble of air exploded from her mouth.

She did a sidearm recovery of her regulator, popped it in her mouth, and sucked in the mixture. When she looked up to find the shark, she saw it trailing away, as if its eyes hadn’t seen her at all. A crazy undersea driver, a hit-and-run expert sailing on to his next victim.

Peta hung in the water for a moment to take stock of the damage. Her buoyancy control vest looked as if it had been shredded by the abrasive skin of the shark, but she realized that it had looked the same way when she’d put it on. Undoubtedly, the result of a zillion tourist dives. Otherwise, she was fine, and she was wasting time she didn’t have.

She continued her dive down to the hole. To Simon.

Just past 120 feet, she found the bottom.

She was very close to where the drill had entered the seabed. Swimming by, she noticed that the test well itself had been sealed with concrete. The entrance to the cave couldn’t be more than eighty feet away. Nitrogen narcosis would normally kick in if she lingered at this depth, but this dive was not about lingering. She had to find the cave and take an express train as deep as it went. Once there she’d have to quickly cut back her oxygen in time to prevent problems. That way at least she wouldn’t go crazy with the rapture of the deep. Although, she thought, she could probably do with a little rapture about now.

Right about then, she spotted a tall marking pole left by the drilling team at the edge of an undersea rift. The markers were usually used to track where samples were taken, or places to test for underground oil. In this case, it was a pointer to Simon’s destination, the underwater cavern.

She didn’t like cave dives, not at normal depth, and certainly not at a tech-dive depth. Once you were inside, your options closed. You lost both light and maneuvering room. One of her best friends once did a deep underwater cave in the Yucatán. They fished him out dead the next day.

She looked at the narrow entrance. Tight, but roomy enough to swim in.

Damn you, Simon, she thought. You should have known better. You shouldn’t be in there. You’re too old; it’s too dangerous.

Time to cut the oxygen—and fast. She reached behind and lowered the oxygen to below 20 percent, while bringing the nitrogen and helium mix up an equal amount. She took a breath. The air tasted a little metallic but otherwise fine.

Finding no further reason for delay, she kicked into the mouth of the cave. Her small light barely caught the walls, and she heard the clank as her tanks scraped the top. The cave twisted and turned, and she tried to check her depth gauge, but there was no room to reach behind and grab it.

She felt the familiar pull of a deep dive: stress, anxiety. It’s okay, she thought. Calm down. Focus. No problems here. I’ll just hope I have a good air cocktail going for this depth, because if it isn’t good, it could be too late for me to tell. Disorientation will hit, confusion, and it’ll be underwater mouse-in-a-maze time. And the maze always wins.

Stop it, Peta! Focus! she screamed inside her head.

She came to a fork in the tunnel and looked around. No Simon, no bubbles. Which way to go? One hole narrowed. No way he could have made it through that one. She looked at the other; the walls were smooth, almost polished. That seemed strange. They should have been rough, with coral fingers reaching out like the ones behind her. Instead they looked shiny. She wondered if it could be something volcanic.

She checked her watch as she swam down the strange channel. Ten minutes. That meant Simon had been down what? Fifteen or twenty minutes? He should be on his way back.

Ahead of her, the cave widened into darkness. She kicked slowly, tentatively, up to the mouth of the opening. When she was practically in the opening she became aware of a distant glow.

Using her headlamp to pick up what it could, she saw an enormous chamber, an underwater grotto. A cathedral, but unlike any she’d seen on her own dives or in pictures. It was as if someone had carved a giant, smooth bubble seventy or eighty feet below the seabed.

She shone her light on the glow—much closer now—and picked up another diver.

Simon floated near the far wall. Not moving. Suspended like a lifeless toy in a child’s fish tank.

Peta stayed at the entrance to the cavern, looking at the body of the man she’d come to save. Damn it, Simon, she thought. Why didn’t you let me talk you out of this?

When she knew she couldn’t put it off any longer, she tilted her body and gave a few small fin kicks to sail nearer to him. His lamp pointed down, dully, at the same meaningless spot, but the reflected glow bounced onto the walls. Peta let herself look up for just a moment to see the strange markings on the smooth surface.

They were…she searched for a word.Incomparable . There was nothing she had ever seen that even came close to them. She thought of the markings she’d seen on Mayan tombs, but they were like cave drawings. These weren’t primitive. They were stylized, with odd shapes that could have been metallic devices and—

She stopped. There was no time for sight-seeing. She reached out and turned Simon around. His eyes were wide open and had bulged, probably as he struggled to breathe, getting the mix wrong. She checked his tanks. They had plenty of air and looked like they were set to a good ratio of oxygen to nitrogen-helium blend. That meant it must have been his heart. It could easily have given out on him. The tension, the pressure.

Looking down, she saw that he had something clutched in his hand. A sharp chill ran through her. The material looked similar to the pendant that Arthur had given her. She reached out and tried to pry Simon’s gloved hand from the object, but his fingers were locked tightly around it. For one grisly moment, she wondered whether she’d have to use her knife to pry off his fingers, but one by one they snapped back like catches on a sunken treasure chest. The object tumbled free, spinning; Peta reached out and caught it.

As her fingers closed around it, she had the same sense of the heat being drawn from her skin as she’d had when she held the piece Arthur had given her. Stranger yet was the fact that the shape looked as if her piece could fit right into it…whateverit was. And she could see places for other pieces to fit, as well.

If McKendry survived and could find Selene and her piece of the artifact, that plus Peta’s and Arthur’s and the one Frikkie still had could be put together to make—what?