Robbie laid on his beach towel and watched with interest as two young girls stopped less than 20 yards away. Carefully, he positioned the camera under his shirt, which had been placed in a heap in front of him, and got ready to shoot.

He had been on the beach for around thirty minutes already, but had yet to shoot a single frame. It was only 10 o'clock, and he knew it would be another couple of hours before the early June sunshine tempted out the tourists in greater numbers. But now, he thought, these two beauties are enough to keep me occupied for a while.

He watched through his sunglasses as the two girls carefully laid out their towels on the sand. One of them - a cute little blonde with a ponytail that poked through the back of her baseball cap - had already stripped down to her bikini, revealing the shapely outline of her prominent chest. Robbie placed one hand under the shirt, double checked that the lens wasn't obscured, and gently pushed the shutter release button. Snap.

A little rush of adrenaline coursed through his body. He knew it was a risky business - especially when the girls were in their teens - but at times like this, he thought the risk was more than worthwhile.

At 21 years old, Robbie was a total nerd at heart. He had never had a girlfriend, and the closest he had ever got to having sex was wanking off in front of the computer screen.

But regular porn got boring after a while, and what he really liked was the candid stuff. He had a huge collection of downloaded beach pictures, secretly taken by a worldwide band of dedicated photographers. He had also joined a number of web forums, where the pictures were free to download, but which also had busy forums where the photographers gathered to discuss equipment and techniques.

He quickly learned that this secret photo stuff was a challenging business, and that getting the perfect picture was an art that needed a lot of practice and skill. Soon, he became eager to try for himself, and not long after joining the forums he purchased a compact digital camera with the intent of photographing bathing beauties without their knowledge.

At first, he yearned to be on the continent, where sunbathers had no reservations about being topless, or even nude. But he soon came to realise that while his local public beach may not have been the Côte d'Azur or the Costa del Sol, it still had its fair share of gorgeous females - just like the two in front of him.

In almost 45 minutes, Robbie took over 50 pictures. He was never sure how they would work until he got back into the safety of his flat, but he felt confident that this time he had taken some real good'uns. Both girls were wearing skimpy bikinis - the type that tied together with bits of string - and both girls were always on the move, rearranging their towels, applying sun lotion and taking regular dips in the sea. One of his biggest peeves was when a really fit bird sat near him, but then didn't move for hours on end. He just had to shoot the same damn picture over and over again - it was so frustrating!

But this time, he had plenty to work with. Blonde bends over to straighten towel. Snap. Brunette rubs sun lotion on inside of thighs. Snap. Both girls jump up and down in the surf. Snap. Nipple-slip as wave dislodges Blonde's bikini top. Bingo! Robbie could hardly wait for the girls to get dressed and leave - then he could get the pictures uploaded to the web and start basking in the collective glory of his fellow candid-connoisseurs.

But then something unusual happened...

The two girls had just been frolicking in the sea, and were sitting with their backs to Robbie. Suddenly, they both got up and walked the twenty or so paces to where he was sitting.

"Hi," said the brunette. "Can we join you?"

"Uh, hi," said Robbie. "Sure."

The girls sat down on the sand in front of Robbie, forcing him to hastily ensure that the camera was fully covered and out of sight.

"I'm Chayla," said the brunette. "And that's Emma."

"Robbie ... Nice to meet you," he said.

Robbie was not expecting this. It had never happened before, and he wasn't sure if it was good or very, very bad.

"So what are you girls up to?" he asked, trying to keep his voice as casual possible.

"Just hanging out," said Chayla.

"No school today? How old are you anyway?"

"Fifteen," they both said in unison. "We got the day off. Teacher training day," said Emma.

"Oh, cool," said Robbie. He was in unfamiliar territory - talking to pretty girls! - and not at all sure how to proceed.

"Hey, can we see your camera?" asked Emma.

Robbie's heart froze. "What camera?" he said. "I don't have a camera."

In an instant, Emma's hand shot under the shirt and came out holding the camera. Robbie made a grab for it, but was too slow, and Emma rolled backwards in the sand laughing.

Robbie tried to stay calm. There were no rules against bringing a camera to the beach, and as long as she didn't look at the pictures already on the memory card, he would be in the clear.

"Oh, that camera," he said.

"Been a naughty boy, have you?" said Chayla, teasingly.

"I don't know what you mean. That's not even mine," said Robbie. "I'm just looking after it for a friend."

Both girls started laughing again, this time more loudly, and Robbie started to worry that some of the other beach-goers would take notice. In the past half hour, a number of other people had settled nearby, and Robbie didn't want any more attention focused on him and the camera.

Emma pointed the camera at Robbie and took a photo. Snap. Then she took one of Chayla, who stuck out her tongue and made a V gesture with her fingers. Snap. Finally, she turned the camera on herself and puckered up her lips before pushing the button. Snap.

"How do we see what I took?" she asked.

Uh-oh, thought Robbie, this is not good. "I don't know. Like I said, it's not mine."

She gave the camera to Chayla, who began pushing the small buttons next to the LCD display. Robbie began to shift position, seriously considering leaving the camera behind and making a dash for it. He hadn't cleared the memory for months, and the card contained hundreds - maybe thousands - of photos of women. Of all ages, and all in their swimwear.

But something kept him there. The camera also contained personal photos of him and his family. He lived in a small town, and he would be easily traceable if the girls handed it in to someone. He couldn't face the possibility of anyone - most of all his family - finding out what he got up to on the beach. He needed that camera back.

"Aw, that's a cute one!" said Chayla, showing Emma the self-portrait she had just taken. "And that one. And that one," she said, pointing the screen in Robbie's direction.

Then she pressed the scroll button again. Her eyebrows lifted and she made an over-exaggerated expression of mock-horror. Robbie couldn't see the screen, but he knew it showed the two girls in the sea, their backs to the camera and their firm little arses in the centre of the frame.

"Ooh, sexy!" said Chayla. "You should've asked. We'd have posed for you!"

Robbie just sat there, not saying a word. He had expected the girls to be disgusted and report him to the lifeguard - or even the police - but their reaction was surprising, to say the least.

Chayla handed the camera back to Emma, who continued scrolling through the pictures.

"Mmm, nice tits! Like 'em young, do you?" she said, spinning the camera around for Robbie to see.

On screen was a girl - maybe 12 or 13 - with short brown hair, wearing a skimpy pink bikini, including a thong that rode up between her arse cheeks. She was on the lower end of Robbie's preferred age range, but when he had been photographing her a week earlier, she had given him such a hard-on he couldn't resist getting her on camera.

"Girls..." said Robbie, completely stuck for words. "Can I have it back please? I'll delete all the pictures..."

"Oh, okay," said Emma, holding out the camera.

But as Robbie reached out to take it, Emma whipped her hand away and both girls erupted in another fit of giggles. Then Emma turned away for a moment, before turning back again and handing the camera to Robbie.

Robbie was confused, but felt a palpable relief wash through his body. He could now get the hell out of there and away from the danger of being labeled a pervert.

"Thank you," he said. "Now I have to go."

"But hang on a minute!" said Emma. "Won't you be wanting this?"

She was holding up the small memory card that contained all his pictures. His heart sank again, and he held out his hand for the thumbnail sized piece of plastic. He considered making a grab for it, but figured that any commotion would draw too much unwanted attention. He just stood there, with the hot sun beating down on his back, hoping.

Emma looked at Robbie and then turned to Chayla. "Shall I?"

"Where's the fun in that?" said Chayla.

"You're right," said Emma, and tossed the card to Chayla.

Chayla caught it in one hand and smiled, before slipping the card into her bikini bottoms. She pointed one finger down towards her groin and said, "You want it? You better come and get it!"