Clarissa shifted uncomfortably in the back-seat of her best friend's rusty old Ford. They had been on the road for nearly six hours straight, alternating drivers. Her buttocks felt strangely numb, and her blonde hair was plastered to her forehead drenched in sweat. She sighed and turned to face her boyfriend, Marty. At some point during the journey, they had decided not to cuddle. It was too damn hot for that, although there was a longing for him to put his muscly arm around her shoulders. In the driver's seat Amy was singing along to her music, as always. She bopped away as she drove with a huge grin and shot glances at shotgun - her boyfriend Teddy who merely rolled his eyes at the excitable woman. Amy was the opposite of Clarissa - dark haired, exotic and deeply tanned.

The windows were wide open and bringing in hot air with them. The end of a vacation, Clarissa felt a stab of despair. Work tomorrow. Two weeks of blissful ignorance and swimming in a vast lake. Now home - back to that. She hated work. More than that, she hated her pig-headed boss, Clive. He was always staring at her inappropriately, making her feel uncomfortable and ashamed.

Clarissa was a pretty girl, with bright blue eyes and a small and impressively toned figure. She was good-looking, but didn't like to the centre of attention. That was Amy, not her. Amy liked the limelight, and Clarissa was happy to settle back and watch the show. As long as she didn't have to be a part of the show she would just observe with a wry smile. Amy was her complete opposite and yet the two were best friends. Amy was quite large for her height, enjoyed alcohol and fast food - she would also light up a room by just entering. Her boyish charm had boys falling for her regardless of the paunch around her belly. Amy turned negative attention into a game - laughing at herself with a gleam in her eye. Nothing could ever get her down. Her boyfriend - Teddy - was of similar build to Amy. He was bookish and wore wide-rimmed spectacles that had earned him taunts when he was a younger boy. Now an adult, Teddy wore his geekiness with pride and excelled at living up to the image of a stereotypical nerd. After all, nerds were in. It was the age of the nerd. Originally hailing from Brooklyn, Teddy had moved to Miami when he was sixteen years old.

She saw Amy glance in the rearview mirror and startle suddenly. The car rolled gently to a stop.

"What ya doin', Aims?" Teddy asked with a touch of irritation.

"What's that?" Amy asked. She opened her door and got out, looking back at the way they had come.

Clarissa used the moment to stretch her legs and opened her door with relief. Then puzzlement. They had stopped in the middle of the road. True, nothing else was coming along right now, but that could change. She frowned and looked at Amy who was as pale as a sheet and still looking at the road behind them.

"Aims. We need to get back to Miami." Clarissa walked up to her friend and shook her shoulders gently. Amy didn't respond. She stood stock-still, her mouth slightly ajar. Sighing with irritation, Clarissa turned to see what Amy was looking at ... and froze.

"Go'Jezus!" Teddy swore, his voice laced with anger. "Get back in, gals. What ya doin'?" Teddy opened his door and joined the two girls. They seemed pale and shaken, just staring at the road they had left behind. He turned slowly to face the threat. "For Pete's sake, what da he ..."

Marty was the last to leave the car. The six-foot dark-haired jock had been drumming his fingers impatiently on the back of the headrest. It seemed everyone had fallen into a state of shock and were unable to move. Marty turned and looked out of the rear windshield. He stared open-mouthed at the road they had left behind.

Amy opened her mouth and coughed a little. "I'll say it again. What the hell is that?"

Behind them, in the distance and on the horizon, there was a glowing light approaching. At first, it looked like some sort of fog, edging its way towards them. However, as the friends remained rooted to the spot the glowing mass was descending on them at an alarming rate. It was heading straight for Miami. They were directly in its path.

"Are you seein' dis?" Teddy asked, his voice raw and uncertain.

"We'd better get moving." Amy found her feet again, and got back into the car. "Guys, we need to get out of here!"

"It's the strangest thing I've ever seen." Clarissa squinted, trying to get a better look at the fast-moving monster approaching them.

"Come on." Marty took hold of Clarissa's shoulders and steered her back to the car quickly.

Marty had the best eyesight of them all, and his face was the whitest of all. As the thing descended upon them, he saw that it wasn't a single mass. There were many lights approaching - as if someone had bunched up a load of car lights and had them all shining from the same place. The glare wasn't that bright, and from afar, it seemed like a bunch of fireflies. There was something beautiful about the whole mass - a slight blueish tinge in a sea of light - but something sinister about the way it was bearing down on the four friends.

Something inside Marty told him these were no fireflies.

"Come on, Ted! We gotta go!" Amy shouted at her boyfriend. He was standing still - furiously rubbing his glasses and then putting them back on with shaking hands. The mass was doing at least sixty miles per hour, he guessed. Worse, it was closing in on them and suddenly the car seemed a very vulnerable place to be.

With a last glance at the approaching storm, Teddy at last got back into the car.

Marty observed the phenomenon roaring towards them from the back-seat. Individual lights shone from the whole mass. It was an army of ... fireflies wasn't the word for it. They were different sizes, blue in colour, radiating with an inner light. They had no obvious faces, just a mass, a swarm. A swarm of what, exactly? A host of possibilities flooded his mind. They were like locusts converging on Miami but they didn't seem like insects. Besides, some of the individuals in the group were too large. Marty gasped as he realised one centre individual was the size of a truck. "They're gaining on us! Hit it!"

Amy started the engine and they roared off, oblivious of the speed limit. "That thing is heading straight for Miami!"

"I know." Marty gulped, his face still pale from shock. "What the hell do we do?"

"Miami. We'll go ta Miami." Teddy looked at everyone, his face set and determined. "We can hide from dat thing easier in Miami."

"True." Amy agreed. "I mean, what better hiding place is there than a city? A concrete jungle of, of, hiding places."

"What about our families. They have no idea this is coming?" Clarissa gasped in horror. "We have to warn people."

Teddy reached for his mobile phone. "No signal. This is so fucked."

Clarissa tried her phone. "Same here. Damn it. We can't warn jack shit."

"Then we keep drivin'." Teddy said grimly. "We get ta Miami and we hole ourselves down somewhere safe. Ma parents have a house in da middle of da city - and it had a storm cella'. We can ride dis ting out."

"Are you sure we're doing the right thing?" Clarissa asked in a small voice. "What if we should just drive past and keep going?"

"We haven't got a choice." Amy said brokenly. "That thing is gaining on us. We'll only just make it to Miami."

As the friend's continued the drive in silence there was something odd about the situation they couldn't put their fingers on. It was only when they entered Miami that they realised what was happening.

The roads were deserted.

Miami had no traffic.