THE SHRILL SCREECH OF BRAKING TIRES was nearly lost beneath yet another crackling stroke of thunder, but not so the appalling collision of metal with wood which followed a split second after.

Dressed in my nightgown, preparing for bed, I didn't even think to don a robe, but rushed frantically downstairs and out the front door, there to be instantly struck by a furious torrent of stinging rain that nearly sent me reeling back.  But by the next flash of lightning, I made out the vague silhouette of a car, its front grille crumpled against the maple in my yard.  Pushing into the maelstrom, I reached the driver's side just as the door flung suddenly wide and a figure staggered out and into my arms.

Lightning again strobed the scene, but, for a split second, I didn't recognize my friend from college days.  We had not seen each other in three years, since graduation, but that scarcely explained the disheartening transformation.  Her features were drawn and haggard, her skin waxy and pale, and her eyes started from her head as if shocked by some horror beyond imagining.  But odder than these was her hair, which, formerly a carrot-top red, had now bleached entirely white.  She was a stranger, this woman in my arms, her face a portrait of horror and despair.  If not for the voice which spoke a moment later, I should never have known Penelope Leighton.  But that voice I did recognize, though it gasped out its words with a strained wretchedness shocking to hear.

"Help me, Janet!  Oh, please, you must help me -- before it's too late!"

Five minutes later, Penelope sat in my study hunched over a cup of coffee, wrapped in a warm quilt, her hair damp and webbed with rain.  Her hands shook so terribly she could hardly hold the cup.  Outside the storm continued to rage as it had raged since early evening.  I was amazed to think that anyone would dare venture out in such weather, but moreso the timid girl I remembered from college.  Finally, as her shaking eased, she raised two haunted eyes and regarded me dismally through the skein of her damp white hair.  She began to tell her terrible tale.

"I had to come here, Janet," she said.  "I don't have anyone else to turn to.  You were my only real friend in college and, since then, well, I've tended to keep to myself."  She paused and took a hurried drink.  Then: "I'm sorry about your tree, I really am.  I lost control on the wet road.  I never was much of a driver.  I don't know how I made it this far, in this horrible storm.  And I'm so tired, so terribly tired.  You can't imagine.  I can barely keep my eyes open.  That's why I'm here.  Because I have to go to sleep soon and I'm afraid of what might happen, what will become of me when I do."

Suddenly, her eyes widened, as if just recalling something vital.  She set down the cup with such violence that it sloshed over the rim, but she hardly noticed as, with quivering hands, she drew a brown paper back from within her raincoat.  The bag was long and narrow and, for a moment, I thought she had brought a bottle of something to calm her shattered nerves.  But she merely sighed with relief and clutched the bag tight to her chest, as if its contents, whatever they might be, offered her one last chance at salvation.  Then she resumed her story.

"You remember in college how much I wanted to join that sorority, Phi Beta House?  It was very exclusive and I didn't think they'd ever accept me.  My family wasn't as rich as the girls who usually made it in.  But to my surprise they did accept me, but only on condition that I undergo an initiation ritual.  Oh, you hear all sorts of things about those initiations, and I was plenty worried, but I wanted to join that sorority more than anything in the world.  So I agreed to do whatever they wanted."  Her voice lowered dismally.  "If I had known then where it would lead..."

Again, she took an urgent hurried drink, her hands shaking.  When she again took up her tale, her voice was softer, a mere whisper, her gaze distant, as if seeing things far away and long ago.

"The night of the initiation, I arrived at the sorority house at midnight, just as they had instructed.  They took me up to a bedroom and lay me on a bed.  Then they covered my head with a hood and began wrapping me with bandages, around and around, just like a mummy.  I don't usually suffer from claustrophobia, but the constriction of the wrappings, unable to move my arms or legs, I tell you I thought I would scream.  Still, I wanted to prove myself to them, more than anything I wanted to be a part of something -- and so I bit my lip and kept quiet.

"When they were done, with my head still covered by the hood, they carried me outside and lay me in a car.  For a time, we drove.  I couldn't see where they were taking me, and, second by second, my fear grew unbearably until I thought I would go mad with suspense.

"Finally, we stopped and they took me out of the car and carried me for a time.  All the while, no one spoke, and they had instructed me to remain quiet as well; that was part of the initiation.  At last, they stopped again and lifted me over some sort of concrete barrier.  I heard one of them giggle and another told her to hush.  Then I felt their arms release me and my weight was taken by straps attached to the wrappings, so that I was hanging with my feet downward, my back against some sort of wall.

"Only then did they reach down from above and pull off the hood..."

For a moment, Penelope paused, swallowing tightly.  Still holding the cup in one hand, she clutched anxiously at the brown paper bag with the other, almost like a religious supplicant grasping a crucifix.  Nearly a minute passed before she could find the nerve to continue.

"With the hood off, I could finally see where they had taken me.  Even so, even with a full moon casting its pale glow over the scene, it was a moment before I could work out what I was seeing.  Then, when at last I did understand, the horror was so great I could hardly believe it.

"They had taken me to the Penny Bridge Zoo.  There they had hung me over the side of the crocodile pit, on the concrete barrier where the tourists stand.  It was a long drop down to the water below but, with the straps, I was only hanging about four feet above the still black surface.  I couldn't move because of the wrappings, nothing but my head.  The moon glimmered on the water, spreading pools of light and shadow that reached into the distance.  For a second, I held my breath, listening.  Then, from somewhere out of the darkness, there came a soft, heavy splash.  A moment later, into one patch of moonlight, ripples spread.  They rolled silkenly out of the shadows, silent but fraught with terrible significance.

"I wanted to scream, believe me I did.  I didn't care about joining the sorority, then.  I didn't care about anything, anything at all, except that horrible heavy splash and those slow, silken ripples that kept crawling toward me out of the dark.  But I didn't scream.  I was afraid to make a sound for fear I should attract the crocodile.  I had no idea whether a crocodile could reach me four feet above the water.  I presumed the girls who place me there had thought I would be safe.  But what if they were wrong?  What if it could leap up and grab my bound feet in its snapping, toothy jaws?

"And so I stayed silent.  You can't imagine, Janet, what it was like, to hang there above that black, gleaming surface, hour after mind-shattering hour.  I never saw the crocodile itself, nor did I hear another splash, all through those long, terrifying hours.  But that one splash and those first ripples had been enough.  I knew it was out there, somewhere in the darkness, watching me, just watching with its raised eyes and its long jagged jaws.  And every moment was an eternity of dreadful anticipation, my heart constantly racing, at any second expecting to see the mirror calm surface below my feet explode as the crocodile surged up, its jaws yawning wide to seize me and drag me down..."

For a moment, her voice had risen to a shrill cry of despair.  Now she faltered, struggling to regain control.  She stroked the damp white hair from her face and again clutched the brown paper bag tight to her chest.  She gave a small laugh, hideously edged with hysteria.  The cup was empty but she refused my offer of a refill.  "No time," she said, waving me back.  Then quickly resumed her tale.

"I could only have hung there a few hours before a night watchman found me.  But those hours seemed like days.  He pulled me up and unwrapped the bandages, then took me inside to call the police.  That was when I looked in the mirror and saw -- my hair had gone completely white.  Of course, you never knew because I died it red all the time I was at college.  And I never told you about the initiation.  Came graduation, we said goodbye to each other and haven't spoken since.

"But then, a year ago, I began having strange recurring dreams.  Nightmares, I mean.  The dream always begins the same way.  I am wading through a swamp.  The air is hot and heavy, the water warm as it rolls sluggishly around my thighs.  Mangrove trees with tangled roots rear from the swamp in scattered clusters through which a ghostly mist eerily drifts.  I am dressed in khaki, like some great white hunter from an old Republic serial.  Even a pith helmet.  But I don't have a weapon.  I am intensely aware of that one fact.  I don't have a weapon.

"Suddenly, I hear a sound.  A heavy splash of something massive sliding into the water.  I wheel and strain to look, but can't make out anything through the veils of mist.  For a moment, I am frozen, unable to move a muscle, so great is my terror.  Then, out of those mists, ripples disturb the stagnant surface.  Every detail is sharp and clear, unbearably so.  Tiny leaves and branches, floating on the water, rise and fall with the motion.  Instantly I know -- it's the crocodile.  It's coming to get me.

"I can't explain to you, sitting here in this drawing room, warm and comfortable and safe, how real it all felt.  But it was more real than you can imagine.  I know all dreams seem real to the dreamer at the time, but this was different somehow, more tangible, more...inescapable.

"Frantic with terror, I turn in my dream and start to run.  But the water hampers me, dragging at my legs, slowing me.  Though I don't look back, I sense a vast shape gliding smoothly out of the mist behind me.  Somehow I feel the creature's massive implacable approach just as you sense the approach of a subway while standing in the station, a huge inevitable force bearing down upon me.  I try to scream but no sound comes to my lips.  I try to run faster, but the water seems so thick, pressing back against me.  I know I have to reach the mangroves, but they are too far away.  The crocodile is just behind me, so fast it is like a boat, but silent, so terribly silent..."

Penelope lifted her eyes suddenly, as if waking from the very dream she had so vividly described.  She blinked quickly.

"I have had the same dream over and over again, for the past year," she said.  "I always wake up before the crocodile gets me.  But each time, he draws slightly closer before I awake.  The last time I had the dream, four nights ago, he nearly got me.  He  was so close, I could smell the rank stench of him even on the still air."

For the first time, I ventured to speak.

"But, Penelope," I said, with careful restraint, "you shouldn't allow a little thing like that to upset you.  Obviously that initiation left its mark on your subconscious; but who wouldn't be shaken by something like that?  I mean, that was an awful thing for someone to do.  Your hair turning white -- you must have been terrified.  But this dream, it's just that, just a product of your mind.  It isn't real."

In an instant, she was on her feet, her eyes wide white coins.

"But is it just a dream?  You know what they say?  If a person dreams that they died, they will die in real life!"

I was shocked.  She had always seemed so level headed.  A trace of impatience crept into my tone.  "That's ridiculous, Penelope.  It's not true.  How could you prove something like that?   It's just a silly superstition, that's all.  Anyway, even if it were true, you said the crocodile doesn't get you."

"But it almost did.  The last time, it nearly got me.  Since then, for the last four days, I haven't dared to sleep.  So I went to see a sleep therapist and it was from her that I came up with a plan."

"A plan?"  For the first time, I felt the stirring of a vague unease.  What did she have in the paper bag? I wondered.

"She suggested I take control of my dream.  Have you heard of lucid dreaming?  No?  The sleep therapist told me all about it.  That's where a person can train themselves to remain aware even in a dream.  When they are dreaming, they know it is a dream, and they can make things happen as they wish.  Well, there isn't time for me to learn to do that, but I came up with another idea, with a plan."

Abruptly, Penelope reached into her brown paper bag and pulled out a large, gleaming butcher knife.  I gasped in alarm, half rising from my chair, but she simply smiled and brandished the weapon exultantly.

"When I next go to sleep, I will hold this tight in my hands.  I will concentrate on it as hard as I can, thinking of nothing else.  If I'm right, I will dream about it then, and I will finally have a weapon to fight off the crocodile."

I couldn't believe what I was hearing.  It sounded like sheer lunacy.  And I certainly didn't care to have her waving that thing around in my drawing room.  But she continued.

"The reason I came here tonight is that I want you to watch over me, Janet, while I sleep.  In my dream, I will have to turn on the crocodile and kill it with this knife.  Oh, I know what you're thinking.  A puny knife against a crocodile?"  Actually, that wasn't what I was thinking, but I didn't tell her that.  Urgently, she continued: "The thing is, it is my dream.  All I need is a weapon to let me take control.  Then I can kill it.  I'm sure I can.  What I need you to do is watch me.  If you see any sign that I am in trouble, anything at all, you must wake me up instantly, because that will mean that something has gone wrong."

I don't know why I agreed to her scheme, except that it seemed ultimately harmless enough.  And perhaps, since it was her belief in this crocodile that was causing her so much distress, perhaps it might even work.  She might just succeed in dreaming that she had killed it, and maybe that belief really would free her.  Who could say?  At the same time, I was loath to let her sleep clutching a sharp butcher knife.  Still, so long as I kept an eye on her, I felt she should come to no harm.

A short time later, then, she settled into my bed.  The butcher knife was clenched tight against her chest and, by the way she was obviously concentrating on it, I doubted she would be able to fall asleep.  But soon, she closed her eyes and drifted off.

For an hour, nothing happened.  Outside, the storm continued to flash and bellow, the rain beating heavily against the windows.  But inside, there was only the soft whisper of her regular breaths and the gentle ticking of the clock on the bed table.  So quiet was it, that I'm afraid I must have soon drifted off myself.

I woke suddenly, brought around by a particularly violent crack of thunder.  I looked at my watch, then glanced casually at Penelope expecting to find her sleeping soundly -- only to find her hands covered with blood.

In horror, I lurched up and sprang to her side.  She was obviously having a nightmare.   She clutched the butcher knife so tightly that the blade was cutting into her trembling palms.  The blood stained the sheets with ghastly scarlet splotches.  I cursed myself for falling asleep, for allowing her to go through with this dangerous scheme in the first place.  If any permanent harm had been done, I knew I would never forgive myself.

Quickly I pried the knife from her hands.  She gasped as I did so, momentarily seeming to fight against its loss, but didn't wake.  I set the blade on a bed table and went to fetch a first-aid kit from the bathroom.  When I returned, though, I was astonished to find her twisting and moaning in her sleep, her straining features beading with sweat.

At last, I recalled the promise I had made -- to wake her if she was having a nightmare.  I seized her by the shoulders and shook her violently.  But so deep was she in her dream that nothing seemed to rouse her.  And now there was a bizarre, quite frightening expression on her sleeping face.  It seemed a look of unbridled fear, of abject terror.

For the first time, I began to feel a strange illusive concern.

Previously, my only worry had been that she might injure herself with the knife.  Now, though, all that she had told me began to take on an unexpected and alarming plausibility.  It was insane, I know, to believe that this dream of a crocodile could lead to her real death.  The crocodile was a figment of her imagination.  It wasn't real.  What harm could it possibly do?  And yet...that horrible contorting look upon her face as she thrashed and moaned beneath the sheets, that expression combined with the wild atmosphere of the storm, the crackling thunder, the howling wind, the ghastly scarlet blood...

Hardly even aware of what I was doing, I grabbed up the bloody butcher knife and slipped it into her hands once more.  She seized it with the frantic clasp of a drowning man.  I stumbled back, eyes wide, barely able to credit what I had done.

At that same moment, there was a deafening clap of thunder and the lights went out.  For a space, I could only stand there in the dark, unable to see.  Then, from the shadows, I heard Penelope cry out in sharp startled alarm.  More silence followed.  Then I heard the sheets rustle.  Instantly, the lights came back on to reveal Penelope sitting bolt upright in bed, looking around her with enormous bewildered eyes.  For a moment, her gaze fixed dazedly on the blade in her hands, then rose slowly to look at me.

"I did it, Janet," she told me in stunned amazement.  "I really did.  I killed the crocodile.  I'm free at last!"

And so she was.  Since that night, the dreams have not returned and that was nearly a year ago.  We have seen each other quite a bit since then and are now the closest of friends.  And yet, in all that time, I have never told her, nor will I ever tell her, what happened the next day.  It is best to let Penelope Leighton go on believing as she does believe, that she vanquished a nightmare that night, that she conquered her subconscious, and let it go at that.  The truth, I think, is too frightening to contemplate.

For what I will never tell her is that the next day I saw a news report on TV.  In the night, inexplicably, someone had killed the crocodile kept in the Penny Bridge Zoo.  While locked in a cage, at the height of the storm, the beast was stabbed to death... apparently while it was sleeping...