It's early morning in San Francisco, and the morning fog is like torn silk, wandering freely among the steel cables of the Golden Gate Bridge. Detective Erin Harper's black police boots crunched heavily over the wet asphalt, the soles picking up dark red ice crystals, eerie traces of last night's rain mixed with blood.
"Fourth main cable, 30 degrees elevation on the north side." The hoarse and urgent voice of the field commander came over the intercom. Erin looked up, and the four hundred meter high orange-red steel tower seemed like a sharp blade, piercing straight through the fog. The yellow caution tape hanging from the suspension cables rattled in the wind, like a rattlesnake crucified on a cross, exuding an aura of danger.
The gears of the elevator made a piercing rubbing sound, as if groaning in pain. The forensic assistant was standing on the elevator, taking pictures of the severed arm hanging in mid-air. It was a woman's right hand, with a Tiffany platinum ring on the slender ring finger and dark blue paint chips embedded in the nail crevices. Erin's temples jutted; same position, same pose, this was the third stump.
"The cuts are cleaner than the first two." Medical examiner Marnie removed her blood-covered latex gloves, a hint of a nerve bundle still clinging to the tip of the metal dissecting forceps, "The killer used liquid nitrogen freezing this time, and then laser cutting--not a tool you can get at an ordinary hardware store."
The sea breeze was salty and blew the notepad in Erin's hand. She suddenly noticed the striped scar on the inside of the wrist of the broken arm, an old five-centimeter-long wound that instantly reminded her of the rainy night twelve years ago. The same rusty scrape on the guardrail of the Bay Area Bridge the night her father disappeared, as if it were a cruel mark of fate.
"Detective!" Technician Joey's voice came from below. The freckled young man was sprawled on the access platform, spectrometer in hand, scanning the surface of the steel cables with rapt attention, "The carbon isotopes of these asphalt particles show ..." He suddenly paused, the knot in his throat rolling up and down, alarm in his eyes, "It's the exact same material used for the bridge overhaul in 2011."
Erin's pen made a deep indentation under the line, "The killer had knowledge of bridge engineering." At that moment, the intercom suddenly burst into a strong current murmur, and the dispatcher's urgent voice froze everyone in place: "Citizen reported his wife missing from Fisherman's Wharf last night, wearing a wedding ring on the ring finger of her right hand ..."
In the basement of the police station, cold light tubes buzzed as if telling endless secrets. Erin pinned three photos of the scene to the case board, the faded holes of the large head pins showing the numerous unsolved mysteries that had been pinned here. When she circled the coordinates of all the found limbs with a red pen, she didn't just form equilateral triangles; instead, by consulting a large amount of urban geography and combining it with the developmental changes of the area around the bridge throughout history, she realized that all these locations were once connected to an abandoned underground piping system, the drawings of which were hidden in the vast amount of information about the bridge's construction that had been researched during her father's lifetime, and this gradually pointed to the location of her childhood neighborhood of her residence, rather than a simple coincidence.
"Here's your coffee." Partner Leo set the mug on the file-strewn table, the reflection of a distorted human face floating on the surface of the brown liquid as if it were a stare from hell. The Latino officer always liked to chew mints at the murder scene, but at the moment his lingering scent reminded Erin sickeningly of morgue embalmers.
Surveillance video danced across the screen in a blur of snowflakes. The man in the reflective undershirt dragged a waterproof bag furtively toward the shadow of the bridge tower. The night-vision lens colored the number on his badge a phosphorescent, ghostly green: 0037. But cold sweat instantly slid down her spine and into her waistband when Irene pulled up the engineering department employee file -- the number belonged to Thomas Wilson, the steel engineer who'd jumped to his death from the South Tower three years earlier.
"Even weirder is this." Leo slapped a ziplock bag heavily on the table, containing the original work badge from Thomas's belongings. Under the police magnifying glass, the number "0037" had tiny scratches under the paint, and it was faintly obvious that the original number before it was tampered with was "0052", as if someone was trying to cover up some ulterior motive.
The ambulance siren suddenly sounded outside the window, shrill and piercing. The hot coffee in Irene's hand spilled over the keyboard, and in the rising steam, she saw some horrible truth reflected in her trembling pupils: the times of the disappearance of all the victims corresponded precisely to the records of the bridge repairs that Thomas had been involved in during his lifetime, as if it were a carefully orchestrated game of death.
The midnight chime came through the bulletproof glass, low and solemn. Erin stood alone in the blue light of the evidence room, a stale, eerie odor surrounding her. An engineering log lay quietly in Thomas's relic box, and on the page where Father's Day was recorded, someone had drawn a drawbridge with blood stains, and the location of the abutments were clearly the coordinates of her family's old mansion, as if it were an invitation from hell. She recalled that her father had said that the area had once been a temporary home for bridge construction workers, and that many of those involved in the bridge's construction back then had lived there, which made the clue's appearance no longer a mere coincidence.