He put the mask down, took the dumbbell anchor to the side of the boat, and dropped it over with a sploosh. The line fed out.

"What we'll do," Lopez said, "is a modified circular search. You're going to be anchorman, Navarre. All you got to do, you follow the line down, float just above the bottom. Not on the bottom. Don't touch that. It's about three feet of silt and muck, and you put so much as a fin in it-poof. We'll be in a blackout."

The line went slack.

"Snag." Lopez tugged at it, moved down the boat a few feet, then kept lowering it. "There. That should be the bottom. Looks like a hundred five feet.

We'll let the silt settle for a few minutes."

Lopez cut the top end of the rope, tied it to a yellow inflatable buoy the size of a bike tire. It had a diverdown flag fastened to the top. Lopez made the line taut and set the buoy over the side.

"I go down with you," he said. "I take a second line out from the anchor-a tender line.

I do a quick sweep of the area, as much as the trees will let me. The signals are like this. One tug from you or me means stop. Two tugs, take up the slack. Three tugs from you means come here. From me, it means let out some slack. Four tugs, pull me in slowly. Five tugs, I'm in trouble and can't get back. You get five tugs, pass that signal along to the surface by pulling hard on the main line, and Clyde comes in. He'll be fifty percent ready to dive the whole time we're down. Counsellor, you know enough to help Simms suit up?"

Maia nodded.

Lopez stared at me intently. "You got all that?"

"I think so."

"Give it back to me," he ordered. "All the signals." I did.

"Now the basic dive signals," Lopez said. "Let's make sure we're using the same ones."

I ran through the ones I remembered. I needed a little prompting, but in the end, Lopez seemed satisfied.

"We wear a minimum of gear," he told me. "It's easy to get snagged down there. You get caught, don't panic. You might get in a zerovisibility situation. You might not even be able to see the rope. In that case, you find east on your computer compass. The console is illuminated-stick it against your mask if you need to. Then you swim east.

You'll hit the shore that way no matter what, and you just follow it up. How fast do you ascend?"

"No more than thirty feet a minute," I said. "Safety stop twenty feet from the surface for at least fifteen minutes."

"All right," he said. "You know what nitrogen narcosis feels like?"

"One margarita for every thirty feet. Sort of like walking through the Texas Folklife Festival."

Lopez did not look amused. "You start feeling like you want to offer your regulator to the fish, the mud starts looking beautiful- you ascend to a higher level. Got it?"

"Got it."

He exhaled. "Now let's hope we don't need any of that. Suit up."

Lopez walked over to Clyde, who was getting the tanks ready.

I sat next to Maia, started pulling on the legs of the shortie suit. "You okay?"

"Just get down there and get back up," she said. "Quickly."

She wouldn't meet my eyes. Her hair was tied back loosely, wisps of it trailing down in front of her ears like brown silk thread. She wore white shorts, an oversized blue Tshirt, flipflops. I could see the crescent scar on her calf that I'd traced with my finger many times, the single tiny mole on her forearm, the perfect diamond shaped corners of her eyes that had always reminded me of comet tails.

Maia caught me looking, gently pushed my face away. "I think you've got somewhere to go."

"Come on, Navarre," Lopez growled. "Get to it."

Two layers of fivemillimetre neoprene later, I understood why he was impatient.

Standing on the boat deck in the June heat, I felt like I was being microwaved in Saran Wrap. I pulled on the hood, attached the regulator to the tank, slipped a knife in one legholster and lineman's pliers in the other. I pulled on orange DayGlo gloves and wondered if they would blind the fish. Clyde hefted a steel tank for me while I got buckled into my BC.

Clyde said, "You watch it down there. You pay attention."

"Thanks."

Then he gave my straps a violent tug, made sure everything was too tight for comfort, and went back to his own equipment.

I doublechecked my gauges, reset the computer.

Clyde laid out a firstaid box, an emergency oxygen tank, and mask. I wished he'd waited until we were over the side.

"Right." In his hooded suit, all black except for blue stripes, Lopez looked like a buff, hightech sea lion. "Time to party."

"You want to use the water slide?" I asked.

"Shut up, Navarre."

Lopez checked my equipment. I checked his. There was an entry bench on the party boat, of course. Lopez looped his fin straps around his wrist. He sat on the bench, facing the deck, scooted his butt to the end, put one hand on his mask and the other on his weight belt, and did a backward somersault into the water.

Next it was my turn.

The splash imploded around me in a haze of cold, white foam. I was surprised at how fast I was sinking, then realized I hadn't inflated my BC. I groped for the button, kicked without the benefit of my fins, which still hung around my wrist. I had a moment of panic, then remembered that I could in fact breathe. I got under control, sent a burst of air into the vest, floated upward, and met Lopez on the surface.

He kept his regulator in his mouth, which spared me several scathing remarks, gave me the okay sign. I responded. We pulled on our fins.

Lopez went to the buoy, pulled the rope taut, retied it. We gave the okay signal to Clyde and Maia. I thought about the last time Maia had watched me descend, at Windy Point, going down to meet Matthew Pena.

Lopez gave me the thumbsdown sign. I reciprocated.

We held up our inflator hoses, released air, and began to sink.

We faced each other as we went down, following the yellow line. Almost fully covered in neoprene, my body felt unreal, only the area around my mouth feeling the full effect of the cold.

Bubbles trickled up my fingers. Lopez was a dark, multilimbed thing across from me, vaguely outlined in spears of light from the surface. Below, a chasm-black and green brush strokes of water, shifting.

Lopez unclipped the flashlight from his belt, tapped it. I got out mine. We switched them on and continued descending finsfirst.

About every ten feet I had to pinch my nose to equalize the pressure in my ears. Soon, the light in the world was reduced to our two yellow flashlight beams-like a cockeyed car driving through green JellO. Occasionally the ghostly form of a catfish or Guadalupe river perch would flit into our light, then turn as if scorched and vanish.

We hit a thermocline at thirty feet. The temperature line was as sharp as a razor-cold above, frigid below. Just when I'd gotten used to it, when I thought I'd gotten as cold as I could get, we hit the second thermocline layer at seventy feet. And we kept descending, following the yellow rope that was no longer yellow at this depth, but pale gray. Even the blue stripes in Lopez's suit were starting to seep away. I decided the rope couldn't have been this long, ravelled in its net bag on the surface.

Slowly, the darkness below us intensified. I swept across it with my flashlight. One moment, nothing but water. The next moment, there they were-black Ys and Xs of wood; branches; twigs doing aimless somersaults. It was a huge, skeletal landscape of lines and cracks, as if a whole sphere of the water had been frozen, then shattered.

I was looking from above at the bare branches of an enormous tree-a bird'seye view. It was a goddamn pecan tree at the bottom of the lake.

I heard an omnipresent plink, plink: Lopez, getting my attention by knocking the butt of his knife against his air tank. I could barely see him, two feet away from me, until I shone the flashlight on him. He was waving one palm horizontally over the knife-the sign to level out.

I was descending too fast, getting too close to the tree. I kicked up, added a little air to the BC, and my fin brushed against a branch. An ancient, open pecan pod snapped away from the top of the tree and went spinning into the void, its petals like a black claw.

Another two seconds and I would've been ensnared in branches.

I flashed my light around and momentarily lost the rope, and Lopez. Then, just as suddenly, there he was. I could see the danger- how easy it would be to get disoriented, tangled, panicked.

We floated, suspended above the tree, shining our lights on each other. I felt colder than I'd ever felt. My whole body was tight, like I'd been shoehorned into a much smaller man's wet suit.

Lopez signed, Okay?

I should've made the soso gesture, but I responded Okay.

Lopez tapped his computer. I checked mine. My air supply read 2,700 psi. Depth: ninetyeight feet. Lopez pointed to the rope, then down to the tree, then used more gestures to indicate that since the rope had gone straight through the branches, we'd have to navigate around the circumference of the tree and underneath. Was I okay with that? I made the Okay sign.

He tapped his watch, held up ten fingers. Ten minutes. The clock had started running.

We turned horizontal, angled ourselves down, then carefully descended around the periphery of the pecan tree.

It must've been a monstrous specimen when alive, and down here in the murk it seemed even bigger. We tried to keep a safe distance, but the tree kept surprising us.

We kept getting brushed and snagged, clawed at, almost impaled on branches that were worn to silty pikes from the decades underwater.

Then, at last, we were below the lowest boughs, shining our lights on a trunk so large our hands might just have met had we tried to hug its diameter.

Lopez plinked to get my attention again, gestured with his flashlight. He was warning me not to get too close to the bottom. It wasn't really solid below me-just a fuzzy layer of silt, lumpy and pitch black, like the remains at the bottom of a barbecue pit. Our line from the surface went straight down into the stuff, the anchor completely submerged.

Lopez gestured for me to come over and stay by the rope. He produced a second line from his supply bag-the tender line. He made a loose shepherd's knot, and slipped it around my wrist. He checked his computer, apparently calculating our GPS, then pointed off in one direction, pointed to himself.

I nodded.

Lopez measured out two yards of line the way they do in fabric stores-running the line from his nose to extended thumb. He handed me the slack. Six feet seemed a ridiculously small distance to start with, given how little time we had, but then Lopez moved away, and within a few feet he was gone.

There was no logic to it, what you could see and what you couldn't. In one direction, through a clearer patch of water, I could almost make out the trunk of the next tree in the row, but I couldn't see Lopez six feet away. If I shone my flashlight directly on him, I could just barely make out a smudge of black.

He gave me two quick tugs on the rope. I fed him another six feet of line, and then he was gone completely. I was alone.

I shone my light up through the branches of the ancient pecan. It must've been frozen in winter, fiftyplus years ago, but it looked like it might've been submerged yesterday. There were still hardened knobs of pecans clinging to a few branches, more delicate black claws of open pods-things you would not think could withstand the flooding of an entire valley. The texture of the bark was still discernible. I wondered if the McBrides had picnicked here once, looked up at the sun through the branches, been grateful for the shade back on a Texas summer day before they'd had airconditioning, when Austin had still been a small town a day's wagon ride away.

I reminded myself, a little dreamily, that I'd come down here to do a job. I checked my console-one hundred two feet below. The timer read 12:04 minutes, total dive time.

My breathing had almost slowed to normal. I was relaxed. I started smiling for no particular reason, staring up into the branches of the tree.

Then I was brought back to reality by one sharp tug on the tender line. It meant more than just stop. We hadn't discussed it, but I was afraid that kind of tug must mean, 1 found something.

I waited. The cold enveloped me.

I calculated that Lopez was fifteen feet away now, but I couldn't see anything except the faintest bleached spot in the dark, perhaps his flashlight.

He gave three tugs, the signal that I was to come to him.

Not quite sure what to do with the line, I tied my end to the lead line, then, slowly, kicked my way into the gloom, my hand cupped loosely around the tender as I followed it out. Ahead was a tall streak of darkness-the trunk of the next tree. There was a smaller shape, too, with a tiny shimmer above it-Lopez and his bubble stream.

I got close enough to see him. He was floating right in front of the tree trunk as if examining it, his back to me. I kept my flashlight beam on him.

The beam of my light must've caught his attention, because he turned.

And that is when I realized I was going to die one hundred feet underwater.

Lopez's eyes were wide inside his mask, hardly human. One orangegloved hand held his dive knife, the point level to my nose, the thin blade toward me, serrated edge out.

Just beyond him, in front of the tree's trunk, was the thing.

It wore a wet suit, its limbs floating loosely in the current. A cord was wrapped around its legs, tying it to the same anchor that had sunk it into the muck. There was a severed regulator rope floating like a dead vein, and a metal dive knife impaled to the hilt just under the thing's sternum. The face had lost all definition, and the hair was a billowy, colourless mass until the beam of my flashlight touched it; then it flared orangered. And the eyes turned to glass. The mouth opened, and I was sure those white hands reached out to me.

I screamed an explosion of bubbles, kicked, flailed away, and suddenly found that I wasn't moving. I couldn't see the dead face anymore, just endless crosses and hooks of black wood, and something was holding me fast from behind. I lost my mouthpiece, clamped my teeth, panicking, ready to inhale lake water, then somehow managed to find the regulator again and breathe.

My flashlight beam crossed with Lopez's. He emerged not three feet away, still holding the knife pointed toward me, a look in his eyes that I could not mistake.

I kicked, swiped at him with my fins, heard a crack that came from everywhere, and then I kicked again and found I was free. The world exploded in an ink cloud. My flashlight slipped out of my hand.

There was no sight, no sound except my own exhale bubbles and the steady suck of air into my lungs from the regulator, dry and steady.

I tried to breathe normally. I'd stirred up the bottom. What had Lopez said about that?

Swim east. Could I trust him? I'd seen the shore. It was east.

I groped along the top of my tank until I found the pressure gauge that led to my computer console. I brought it in front of my face, pressed buttons on the side until I found the one that made the console illuminate.

Suddenly I wasn't alone. I had faint, green dials to keep me company. I turned until the compass said I was pointing east. Then I started kicking slowly in that direction, still completely blind.

I heard the plinkplinkplink of Lopez's knife on his tank. Was he in front of me? Or behind? The plinking sounded more urgent than it had before. I slid my own knife out of the sheath on my leg, but my hand was so cold even through the glove that I couldn't feel the handle, much less see it. I let it go in the darkness.

I kept kicking-three cycles of leftright. Twelve cycles. I checked the console and found I had about nineteen minutes of air left. I'd been underwater for only sixteen.

I began to see again-the gentle slope of the lake bottom under me. Rocks the size of sofas rose out of the silt, and moving among them, catfish as big as I was. The black was turning to green. I could see the lower spectrum of colours.

I checked my depth and found that I'd risen to sixtytwo feet. I stopped, and had no idea where I was. I was supposed to do something- Go up. Go up slowly. I followed the rocky slope.

At thirty feet I stopped, sat on a furry, silted ledge that had probably once looked over the river valley. It now offered a view of a dark green void. I forced myself to time ten more minutes, which according to the computer left me fourteen minutes of air. I knew the math wasn't right, somehow. Then I remembered that I was using less compressed air as I ascended.

Another ten feet of gradual ascent and I could see the surface-a flashing sheet of silver and yellow. The fish were now clear. I loved every speckle on every trout, every whisker on every catfish. If I'd had a package of hot dogs, those fish would've eaten like kings.

I forced myself to wait ten more minutes to expend the extra nitrogen. I stared into the green, tried to remain calm, tried to sort out the reality from the fantasy. What had happened down there?