TITLE: Psycho Killer
AUTHOR: Lord of Kavaka
CHARACTERS: Castle/Beckett
STORY TYPE: Romance/Adventure/Action/Thriller/Crime
SPOILERS: Anything from Season 1 - 7
DISCLAIMER: I do not own them, and I make no profit.
SUMMARY: Sequel to PRIVATE EYES. Detective Kate Beckett joins forces with CIA Agent Rick Castle to stop an international serial killer known as "The Knave". AU. Spy Castle. Castle Summer Hiatus 2015 Ficathon Entry.

Psycho Killer – Prologue

His feet hit the ground hard as he jogged across the pedestrian packed street, eyes flirting around anxiously as his heart pounded inside his chest. Sweat slicked down his back, making his shirt stick to his skin. The frantic voices of confused and panicked agents echoed from the earbud ensconced in his right ear. Many had been caught up in the ambush, and were scrambling to find cover. The boys back in HQ were freaking out, still trying to recover from the shock of the abrupt betrayal by their asset.

Operation Looking Glass was a complete clusterfuck. Nearly seven months of hard work had just gone down the drain. The bastard had set them up. York was going to be livid. Heads were going to roll back at Langley. Over the communications, he could already hear Agent-In-Charge Huxley trying to cover his own ass and shift the blame to someone else.

Narrowing his eyes, he ignored the arrogant prick and glanced around the crowded bazaar, searching for Johann Kriedt. After being found in an underground S&M dungeon in New York City and seized into custody by the FBI last year, the crooked arms dealer had struck a deal with the Justice Department. In exchange for his cooperation in apprehending and testifying against the international criminal known as The Knave, Kriedt would be guaranteed witness protection from any prosecution or retribution, officially becoming a Company asset.

And that was how Agent Rick Castle ended up back in Istanbul, the one place he had sworn never to return. The last time he had been in Turkey's largest city—almost two years ago—his then-partner had tried to kill him. He still had a few scars from that night, not all of which were visible.

Stifling his memories of the last time he had chased through the streets of this very city, Castle quickly dodged shoppers and tourists, dropping his hand to his waist in order to conceal his weapon. He puffed out a breath, and gritted his teeth, working through the fatigue as he maneuvered around a vender hawking his wares to a group of German tourists. Castle heard the distinctive soft pop pop before the man crumpled to the ground beside him. He dropped back, letting out a curse, as he crouched, making himself as small a target as possible.

Alarmed cries emitted from nearby pedestrians as the unseen shooter sliced down another innocent bystander. Another second or two and the crowded marketplace would erupt into mass hysteria.

"Castle… I need a sitrep!" Huxley's voice echoed in his right ear as he dove behind a cart.

Growling, he brought his right hand up to his mouth. "I'm a little busy," he hissed into the miniature microphone concealed in the cuff of his shirt.

With a quick twist of his neck, Castle glanced around the side of the cart. Amid the frightened crowd, he caught sight of a muzzle flash just before a bullet shattered the front façade of the cart. Pulling back, he readjusted his grip on his gun. Spinning around, he took aim, and returned fire. He retreated back behind his cover just as the sniper retaliated, sending a series of bullets into the front of the cart. Ceramic trinkets shattered and the wooden frame buckled under the assault.

"Castle… Dammit! I need that sitrep!" Huxley shouted into his ear.

People screamed as the hidden shooter began to indiscriminately fire into the fleeing crowd. Castle spun back around and lined up his shot. He squeeze the trigger, feeling the satisfying recoil of his Sig Sauer as his shots ricocheted around the windowsill two stories up on the building across the street. He caught a passing glance of a man in black fatigues retreating back into the second story room.

Clenching his jaw, Castle pushed off from his hiding spot and darted across the street. He raised his wrist up to his mouth. "I'm in pursuit," he relayed back to HQ. "Male. Mid-thirties. Dark brown hair." Yeah, he got all that from only a fleeting glance of the man's face. He was that good. Also, it helped that it was a face he'd likely never forget.

The shooter was Raymond Kilmer. His traitorous partner was now apparently in the employ of Johann Kriedt. And this was the second time he'd tried to kill Castle during a blown covert operation in Istanbul.

Castle lowered his shoulder and plowed through the door beneath the window he'd spotted Kilmer, sending it off its hinges. He stumbled into a living room, finding the slumped form of an elderly man on the floor. Single shot to the back of the head. Clean and professional. The older man had probably never saw it coming. Kilmer had always prided himself on his stealth. Holding his gun up in the ready position, Castle dashed up the stairs. He heard a window shatter up above and double-timed it.

He rammed through the door, and rushed into the bedroom. The window on the left was smashed open. Castle arched his neck and glanced down at the alleyway, easily spotting Kilmer running north, away from the street market. He relayed the info to HQ and ran back down the stairs.

Bursting out into the street, he swerved right to follow Kilmer. The shoppers and tourists were still swarming the bazaar in a mad surge of panic as they tried to escape the chaos, unknowingly aiding the assailant's escape. Castle rushed between terrified people, trying his best to keep up. He was not as brutal as Kilmer was in his determination to reach the north gate of the bazaar. His former partner violently shoved panicked shoppers out of his way, shooting at those who were too slow. Castle gulped down deep breaths as he pumped his legs, running as hard and fast as he could to catch up with Kilmer.

"He's heading for the north gate," Castle shouted into the hidden microphone in his shirt cuff, praying that Huxley wasn't too busy trying to cover his ass to send backup to the location in order to block Kilmer's get away. He got no response.

Gritting his teeth as he growled in frustration, Castle weaved through the throng of horrified people. He saw the north gate. A black Mercedes-Benz G-Class SUV was parked there, backdoor open and waiting. Squinting, Castle could just barely make out the sandy-brown hair of Johann Kriedt as the arms dealer climbed into the backseat. Kilmer wasn't far behind. The rogue agent jumped up, gripping the top of the roof as he twisted his torso around and fired a series of shots in Castle's direction.

Right in front of him was a tear-streaked face little boy, standing in the middle of the street, lost and wailing for his mother. Castle moved quickly, grabbing him and wrapping his tiny body close to his chest as he rolled to the left, just as the spray of bullets struck the ground where the boy had been standing. Keeping the child shield with his broad frame, Castle craned his neck over his shoulder to see Kilmer smirk back at him with a cruel smugness, before he ducked down into the SUV and slammed the door shut. With a heavy sense of defeat, Castle watched as the car took off, vanishing around a corner.

Standing up, he released the boy, watching as he darted over to a distraught woman wearing a black hijab. Castle let out a breath, relieved to see the boy was reunited with his mother. He glanced back at the north gate with a vexed scowl, sighing in displeasure. Not only had Kriedt escaped, but so had Kilmer. Seven months. Seven long months of work gone in a flash. They were no closer to capturing The Knave than they had been five months ago when questionable intel suggested the fiend was in Beirut. York was not going to be happy.

Huxley's voice returned in his ear, demanding a situation report. Annoyed, Castle tugged the earbud out. The senior agent could just stew for a while. Glancing down at his Sig Sauer, he flicked the safety on, and then tucked it into the back of his trousers, adjusting the loose fabric of his shirttail to conceal it.

And then, like he'd been trained, Agent Rick Castle disappeared.