The killer stood in the hallway; he nervously licked his lips adjusting the facemask to make sure it covered his face correctly. Bending down, he picked up the parcel in his left hand, making sure he had hold of the lighter end of it, before pressing the buzzer repeatedly with his right forefinger. He then angled himself so that his left side was slightly more towards the door as he hid his right hand, the one containing the bowie knife, behind his leg.

He'd perfected his MO over the last 9 attacks, but couldn't resist going through it one more time in his head.

1. Buzz your way into the apartment block, someone would always let in a courier, and he was dressed the part so, even if someone checked the CCTV, they'd see what they expected to see.

2. Walk around the building with purpose, no-one questions a courier with a parcel.

3. Start on the top floor and go to an end of corridor apartment, then listen at the door to see if you can hear multiple people in there.

4. If the apartment is quiet, knock and, if they answer the door, assess the mark.

5. If they aren't suitable for the ritual, depending on their demeanor, either say you've a parcel that has to be signed for by "Mrs Dalwhinnie" or make out you're on the wrong floor and leave.

6. Repeat steps 1-5 until you find the one.

He had been planning these attacks for a long time and had deliberated on the best way to achieve his aims without being caught. He'd determined, if anyone thought to look beyond the obvious image of a cycle courier delivering a parcel, then the florescent clothing would distract the observer from his height and build. The cycle helmet covered his hair so there were no clues as to it's color or length, and the pull up mask he'd had printed with the approximation of the lower portion of a man's face was enough to fool a casual glance, or someone looking through a peephole, into believing they could actually see his face.

He was proud, because he knew he wasn't some 'sicko' who couldn't control themselves. After all, he'd taken the time to carry out research into how to locate and capture the one. He'd taken the time to find out that the easiest way to gain entry to a property was to make sure the weighted parcel was slightly too large for a woman's hand which threw them off balance. Then, with the addition of the counter weight, it felt heavy when they took it from him, so they were even more off guard.

He had even adapted, considering and then adding an extra step to his already perfect pattern, so that he would now let go of the parcel. He'd discovered, due to a divine revelation, on the one he called "3rd time lucky", that they would instinctively watch the parcel or try to stop it falling. That meant that they tended to reach for the parcel with both hands, thus letting go of the door, or their gaze followed it to the floor. Either way, it distracted them for a crucial second or two, enough time for him to push his way into the apartment and threaten them with the knife into compliance. After that happened, then the ritual took place. For some reason they never survived it.

He'd even made up his own business cards to leave in them. It was a nice quality white card, which said, "Courier Killer" in black Papyrus font, with a bloody knife embedded in a parcel outlined in red underneath it – classy and clear, he thought. He didn't want the media or the useless cops to choose his sobriquet, they'd only come up with something stupid.

His attention flicked back to the present, he could hear someone approaching the door. They stopped and he figured they were checking the peephole so, as usual, he held parcel up in their line of sight which, incidentally... not!... also obscured his face.

He could hear as the locks were released and concentrated on the door handle as it started to turn. His stomach fizzed and jumped with excitement, the moment was almost here, but he had to be sure it was the one, so he took a deep breath and urged himself to keep calm, keep calm in case it was another false offering.

The door swung inwards and, at last, he could see them. A slim woman, with dark, shoulder-length hair that brushed against her shoulders. He noticed that unusually, she was close to his height, but that didn't matter. She was the one. She was his.

He casually leant forward, putting his weight on his left leg, holding out the parcel and extending his arm across the threshold, making sure to keep the knife pressed tightly against the outside of his right leg. "Package for Mrs Dalwhinnie" he intoned, following his pre-planned speech.

The woman looked at him perplexed as she moved forward, her left hand resting on the edge of the door. "I'm not Mrs...", she started, her gaze moving towards the parcel's address as her smooth brow furrowed slightly.

He edged in her direction, gesturing with the parcel. She hadn't reached out to take it from him yet, which was unusual, but he knew the rest of his plan would run flawlessly. As flawless as her skin was, he thought running his eyes over her face and neck. He could see the pulse beating at the base of her neck, delicate, transitory. Soon he would own every beat.

He abruptly reined himself in. He mustn't get distracted by thinking about the ritual, that had very nearly ruined number 4. "4, 4 shut the door", he mentally chastised himself.

He relaxed his grip on the parcel and, as it started to tumble towards the floor, he shifted his weight, moving towards her. Bringing the knife out from it's hiding place, so that it was a menacing presence in front of his body. He continued to propel himself forward, ready to threaten her to make her go backwards into the apartment if she didn't naturally retreat, expecting her attention to be focused on the falling parcel.

However, when he looked at her he saw two blue eyes focused intently on him. Eyes that turned from the bright blue of the sky on a hot summer's day, to the icy color of the water in the Bay in winter, when they saw the knife in his hand.

Nevertheless, he pressed forward, gesturing with the knife for her to go back into the apartment.

He saw her lip quirk, unusual he noted, but she retreated and his confidence soared again, he had the control, and soon he would have her, and she would be number 10 on his list. Soon, she would be "The Perfect 10".

He pursued her as she withdrew into the apartment, creating an invasive presence in the hallway, roughly kicking the door closed behind him. He was so caught up in her submission to him, and the tantalizing trace of her scent in the air, that he didn't notice that the dropped parcel prevented the door from closing properly. But she did, and she knew who was even now coming up the stairs, someone who would shortly walk into their apartment unaware of the situation. At which point she knew it was all going to get very messy, as Tasha didn't take kindly to strangers with knives threatening her wife.

To his displeasure, she had stopped in the passageway, but she wasn't screaming or begging for mercy from him, as some of them had done. Now he thought about it, he noticed something else that was strange. She didn't seem to be in the least bit scared. In fact, she seemed to be sizing him up.

No matter how hard he tried, no matter what lies he told in prison, he could never properly recall what happened next. There was a hard tap on his wrist and suddenly the knife wasn't in his hand anymore, he heard it as it landed, bouncing across the wooden floor, but he was transfixed by the look in those blue, blue, eyes. Eyes that were moving closer, in fact, eyes that were right in front of him. Then, there was nothing.

As he fell unconscious to the floor, she saw their front door start to open, as a female voice said "Ria honey, I'm home. Have you seen the newspaper today? The headline's about a serial killer, that's on the loose in Manhattan. Hey, what's this parcel doing in the doorway?"