A perfect ghost

(This was written for one of my exams on the spot... Ofcourse I had to change some parts which were irrelevant to the story but had to include in my essay for it to correspond my the topic... Whatever I wrote I am posting... I dont want to change it... And please tell me if this idea is borrowed from some Hollywood flick or any book.... Cuz I cant remember for now....)
The lights appeared out of darkness. Now a car’s body could be perceived in the darkness. The girl standing at a distance on the road smiled. The car halted and from it shouts of some boys were heard, “What are you doing at the middle of the road lady? You could be run over.”
“Kind sirs, I am all alone here and I need a ride home. So please can you give me a lift”, the girl said. The three boys in the car, who were of the same age as the girl, hesitated but at last agreed. She sat in the back seat with a boy who was recording everything in a handy-cam. “So, what is your name?”one of the asked. “Lizzie”, she answered shortly.
The boys first had a shocking expression but didn’t actually say anything. “We aren’t very fond of girls named Lizzie,”said one of them. “Why? Because you got one Lizzie killed because you were drinking and driving?” she asked. The car came to a stop. All three boys had an astounded face as if struck by lightning. “And then you threw her into the river in fear you would be charged of murder”, she said non-chalantly, “Do you remember how she looked?” “Like you”, whispered one of them. “It’s a ghost!” one of them exclaimed and pushed her out of the car, “Come on drive fast!”
They drove but their car lost balance and turned over. All three were dead.

“So that was a ghost we see in there?” asked Susan to Ronnie, pointing out to the girl recorded in the handy-cam. They were just two friends who had found it in a bush near the accident site that morning. “Well yes, quite a ghost,”said a female voice. Susan and Ronnie turned around and saw something which nearly froze them to death. It was Lizzie, talking to them. Susan and Ronnie’s dead bodies lay near the bush where they had found the handy-cam, with the handy-cam clutched in Ronnie’s hand. They had been killed with a knife.
‘A perfect mystery for ghosthunters to solve. They drowned me in the river but couldn’t kill me. The police can’t catch me. I am a ghost in the eyes of the world now…”Lizzie thought smiling to herself. Before daylight she would leave the country, being happy that she had her revenge on the killers. Cold-blooded as she was.