Devising an idea with a clear narrative structure

What generic conventions are used to make the horror element clear?

Blood,

Murderer - Chris

Weapon - Pen knife

Setting - in the woods, on a camp-out because they break down going to a party.

Characters:-

Paris- holds a chihuahua called Princess, both wear pink, blonde hair with extensions in, and a face full of make up, also with cleavage on show, bit of a blonde bimbo.

Chris - Paris' boyfriend, jock, likes to show off his muscles, wears vests, at every opportunity he takes his top off, likes to think he's brave and the leader, very jealous. (hiding something)

Dwayne - black hunk, having a fling with Paris, very funny, always joking, best friends with Chris, likes to sleep around a lot.

Whitney - Paris' best friend, not as dozy as Paris but kind of intelligent, thinks about things more, black girl, goes out with Dwayne.

Mary - asian girl, pretty but doesn't get the boys, is very intelligent, sensible, always thinks things through too much.

Story-

Five friends going to a party, but the car breaks down on the freeway in the middle of nowhere, it's raining and dark, they are forced to camp out in the nearby woods and decide to have a party with the alcohol they were taking to the actual party.

In the party when people have been drinking, Paris is becoming too close with Dwayne when no one notices(except Chris..). Mary and Whitney need the toilet so they go into the woods to go, Chris pretends to go 'get more firewood' leaving Dwayne and Paris together alone.

When Mary and Whitney return they see Dwayne and Paris getting too close and decide to say something to them, Paris and Dwayne start arguing with them and Whitney and Mary decide to go sleep in the car, fuming at them. Dwayne follows trying to win Whitney back leaving Paris alone, later on Chris doesn't return.

Screams from the woods occur causing Whitney, Mary and Dwayne return to Paris' protection, when they return her and Princess are lying dead on the floor in a pool of blood.

Smeared on the side of the tent is the words 'You're next' in blood. Dwayne starts shouting, Chris returns and starts shouting and crying over Paris, then he goes away saying he's going to try and fix the car so they can get help.

Dwayne follows behind, so the girls follow, the girls walk forward;scared of the woods and they look back and Dwayne is holding his stomach which is full of blood and knife wounds, he then falls down dead. Whitney and Mary run to the car frantically where Chris is waiting for them, asking if they're safe. Whitney notices a knife covered with blood in Chris' back pocket and confronts him, in a massive argument whilst Mary is screaming, he kills her.

Leaving Mary and Chris alone, he goes for her next, shouting at her, she gets into the car, and turns on the engine, noticing that the car had never broke down, Chris is attempting to get in, smashing the windows and screaming, she then runs him over and speeds off into the distance not knowing if he was alive or not..