Disclaimer: The Mousetrap is the property of Agatha Christie and they who she bequeathed the rights to. This is just a work of fiction intended to flesh out the story. No copyright infringement intended.
Clack, clack, clack. Echoing in the narrow alley were the footsteps of a pair of woman's high heels. The movement of the lady's skirt whispered in the background of the steady beat. Briskly, they took the wearer further away from the dim glow of the main street lamps. A low, wistful whistle interrupted the no-nonsense patter. First a low note, followed by two even lower than their predecessor. Clunk of sole and ground accented the tune.
"Who's there?" the woman called out. Her query was answered only by more whistling. Turning around, she peered to see the origin of the tune. Warily, she took hesitant steps back, matched by the determined ones of the newcomer. Quickly, the two of them found themselves against one of the grimy walls. "What are you doing? What business do you have with me?"
At such close proximity, she saw her pursuer was bundled up heavily. The only way she could distinguish physical features was the pale scarf--marking the face. In a crazed face and its accompanying voice asked, though the words were highly muffled, "Do you remember him? Was it fun?"
Sputtering, the cowering woman managed to say, "Who are you? Who is 'he'? Tell me what you're talking about!" Her arm was fiercely grasped, causing her to cry out in alarm. "Unhand me!"
"Hush madam," her attacker placed a hand over her mouth. "We wouldn't want to attract attention, now would we?" The feral tone caused her to whimper and shake her head desperately. "No, we wouldn't want to. That was always said. You ought to remember him. Try and remember if it was fun. You will have to tell him if it was fun." Ragged breathing led into throaty chuckles. "Oh yes, do remember." Muffler and hat were pushed aside. "Because you're going to see him."
Terrified, the woman came to a realization. She went to take a breath to scream with, but---BANG!! A revolver fired, with screams accompanying the shots, three more times, piercing the night's silence. Then, there was nothing but the thump of a body and heavy breaths.
Calmly, the revolver was concealed. A notebook was extracted from one of the many coat pockets. Gloved hands opened it and meticulously took pen to paper and began to sketch. It was ripped out and laid to rest on the dead woman. Casually, the murderer walked away, taking up the whistled tune once again. On the paper were not only words and a sketch, but a bar of music. A bar of music that matched the song being whistled.
TWEET! TWEET! TWEET!
"Over here boys," called a detective. Shrill whistles brought the constables running in full force. A crowd of people had amassed, curious as to the fuss. "We've got a homicide." Silence fell over the people. A few crossed themselves and many heads were bowed. "To work," was the brisk order. Notebooks and pens were brought out and the silence broken by the questions of the constables to the crowd.
Stepping delicately, as to not disturb the crime scene, the detective began to systematically examine the evidence. Making a note of the address, the detective went to close the deceased woman's eyes in respect when a scrap of white stood out in the gloom. "What do we have here?" Crouching down, the paper was picked up and read aloud:
"This is the First."