The water is calm, smooth as glass - but murky and impenetrable in the evening light. After a few minutes spying, I figure it's safe. The lake is hemmed in by trees on all sides - only two spots clear enough to land a boat. Huge tangles of black driftwood bob up and down serenely. Birds. Wind. Evening crickets start their serenade.

I don't like it.

Jean points wordlessly to a small motor boat tethered to the dock a few yards away. I nod once. He motions for Amy to follow and the two of them crab-walk into the clearing.

The lake swells in a hump near the centre - driftwood shudders and floats aimlessly away from it.

Something's moving. Something big.

I say nothing.

They're already in the boat when I leave the safety of the trees. Amy sits alert in the middle and Jean holds the rip cord; I jump in and take point; the motor coughs and chokes like a chainsaw. I cringe. So much for sneaking. I notice an anchor attached to a length of rope by Jean's feet.

The little boat buzzes into the centre of the lake. The further we go, the more uneasy I become - I don't like being so exposed. I scan the murky water. Jean darts his eyes around nervously. Amy stares ahead, gun on her lap - loaded now, which is perhaps why she looks so grim and her hands hold it delicately.

There - the other landing is a hundred yards away. No aldeanos yet. Spray speckles my face; the air is cool over the water. We pass a hunk of driftwood and it rides out on our ripples.

"What's that?"Amy shouts, eyes wide and staring straight ahead. I'm already on it - I let bullets fly into the water just as the bump explodes in a violent splash and an earth-shaking roar echoes over the lake. Amy screams. Jean screams. I scream and spasm on the trigger - the bullets hiss into the water. I can't see if I land any hits - I can see anything until the water rushes away from the rising monster and a head the size of a house opens its great, stinking maw to reveal hideous tentacles wiggling like worms - oh god, it stinks - like mouldering bodies in a sewer - like dead, rotten things.

Two words come to mind as I fumble for another clip.

Holy shit.

Scales fly off its snout as my bullets strike; it doesn't seem to notice. The head rises like a rocket and towers above out little boat - I see its nobby, cancerous underbelly and fire, barely breaking the skin - I shout, "Turn!" just as Jean yanks the motor sharply to the left - the creature spins as it falls towards us - an eye the size of table comes rushing at me - a mad eye, blind with fury and rolled back white. I see my terrified face reflected in it as it comes crashing down.

The boat surges forward. I get a momentary glimpse of the clouds again. Amy is screaming bloody hell and forgets she has a gun. I turn to see the thing fall back into the water like a breaching whale. The splash knocks me over the edge of the boat and I go tumbling into the lake - the sudden shocking, numbing cold makes me spasm. Fingers twitch - I drop my pistol and open my eyes underwater - so dark, can't even see my feet. Every nerve in my body sparks with the possibility of a killing bite. Shit shit shit.

I break the surface gasping for air. Jean and Amy are still in the boat, rocked and terrified a dozen feet away. I whip my head around. My legs feel like bait swinging in the open water.

"Swim!" Jean shouts. He's cut the motor and holds a grenade back, pin pulled. Amy hold her hands over her ears. She's crying hysterically.

I feel the suck of water beneath me as the great beast turns.

When it breaks the surface again it's farther than before - close to the dock on the other side. Something that big needs room to manoeuvre. It doesn't jump into the air but stays on the surface and begins its charge.

"Throw me the anchor!" I shout through a mouthful of lake water. I can feel it coming - the current underneath pulls me towards it and I struggle to swim.

Jean doesn't hesitate - he grabs the rope with his free hand, swings the heavy hook once and tosses it - it lands an arms-length away. I snatch the rope before it the anchor drags it away. Then I turn.

Nothing - not the exploding villagers, not the glow-eyed priest, not the knowledge of an alien entity growing inside me - nothing is as mind-numbingly terrifying as an open mouth the size of a subway tunnel with tentacle-teeth flapping furious coming at me like freight train while I struggle not to be sucked in. Amy cries and Jean shouts something I can't hear, still holding the grenade. My heart thunders in my ears. It's coming. My cold fingers tighten on the rope. One shot. I have one shot.

My mind goes blank with fear as the mouth closes in. The smell - if my stomach wasn't a tight, dry ball of terror I'd puke. The sound is like a building coming down.

It rears back and makes to strike ten feet away.

I dive - with all my might I drag my hands and kick out - the power of it's massive, swimming arms helps pull me down. Utter blackness and noseful of lake water. Rough, ice-cold skin scrapes my cheek as my body is pinned against it's underbelly. Fingers scramble for purchase - I can hear its roar of rage and the thundering of its heart echo through its ribs - I roll and bounce against it and narrowly avoid the swipe of its back legs - at the last second my hand shoots out and I latch on to its tail. Head breaks the surface - gasping, sputtering - but alive and hanging on for all I'm worth as the beast's tail lashes around. I hug it tight to my body and it cuts through my clothes.

The boat buzzes off like a pesky fly - the anchor rope is taut. Jean shouts at Amy, who takes up her rifle with a tear-streaked face and lets bullets fly into the face of the monster. My head goes under when the creature swerves.

With a wordless cry I dig my fingers between its scales and drag myself up the length of its thrashing tail. Wind and water whip my face. When I get to the fat end it's a little easier - I snatch my knife and ram it in to the hilt. I pull myself forward, legs kicking out. So far it's so blind with rage all its attention in on the bullets stinging its open mouth and the sharp anchor tearing into its cheek.

I'm at its hips and try to stand. Like walking on the wing of a crashing plane, but I manage to get to my knees. My knife cuts between the hard scales and out squirts sluggish globs of black blood. Stabbing and crawling - dragging myself up the length of its body - the gunfire takes on a deeper boom and I see Amy hold my shotgun to her shoulder. A chunk of tentacle goes flying over. The beast roars and shakes its head. I nearly tumble off into the water.

"Cut the rope!" I scream. Amy drops the gun and pulls a knife from Jean's belt. iOne - two - three/I slashes and it snaps.

Jean shouts, pulls back his hand, and tosses the grenade into its open, angry mouth.

Boom.

I let go and fly back from the blast of meat and gore - tail thrashes madly and knocks me to the side like ping-pong ball - I hear a crack as I hit the driftwood and my arms shoot out to grab on.

The monster goes belly up - pieces of its head float past, twitching tentacles and chunks of flesh - suddenly the lake is quiet again but for the sound of the sinking monster bubbling out its guts.

The boat floats with its two passengers several yards away. I raise my hand weakly and Jean waves back. Amy sits with her face in her hands. The engine sputters to life and the boat drifts towards me.

Jean grins like a fiend when he reaches out his hand. I take it gratefully. Every inch of me shakes with spent adrenaline. It takes both of them to pull me up, heavy with water and fatigue.

After a few minutes panting on the floor of the boat, I look at Amy. "Are you alright?"

She offers me a weak smile and wipes her eyes.

"Craziest thing I've ever seen," Jean says as he takes up his position at the motor.

"Big fucking fish." I cough heavily into my hand. Sweet Jesus.

"No, my friend - you. Loco de mierda." He pats my shoulder appreciatively. "I think we might make it after all."

I use the time it takes to get to the dock praying he's right.