It couldn't be too late. It couldn't be.

He'd found the gun, after all. It had taken two dives under the water, quickly filling their rapidly-sinking car, but he'd found it. He'd found the gun, then used it to fire two shots. The first shot freed Beckett from her seat belt, which had jammed itself on impact. The second shot blew a hole through the windshield of her car, allowing them an escape route. He'd immediately grabbed Kate's hand, pulling her carefully through the hole in the windshield and up to safety.

He should have known immediately that something was wrong- the water was too murky for him to see, but he could feel Beckett's weight dragging behind him as he tugged them both upward. She wasn't swimming; she wasn't moving. His lungs had felt as though they were on fire, crying out for oxygen, yet he'd kept going, refusing to allow himself to stop moving. He had to make it to the surface. He had to save Kate.

He'd kept pushing himself upward, ignoring his screaming lungs; begging his body to keep going. He couldn't give up. Just as he'd felt himself about to succumb to the icy depths, he'd seen a glimmer of light above him. One more stroke later, and his head was out of the water. He'd taken a deep, gasping breath, gulping in the oxygen. After sputtering and coughing for just a moment, he'd yanked Kate upward, pulling her head above the surface.

It had taken a moment for his eyes to adjust, but finally, he'd been able to make out the glowing streetlight, a beacon of light pointing him to the safety of the shore, only a few yards from them. He'd pulled Beckett closer into his chest, cradling her body in his left arm as he swam toward the light.

Finally, he made it to the shore, pulling himself and Kate out of the water and onto the solid ground. The moment he'd pulled her body up beside him, he'd collapsed, lying on the ground and taking deep breaths, steadying himself. After a few seconds, he turned to face his partner, a grin on his face as he prepared to congratulate her on their survival.

It was only then that he realized that Kate wasn't breathing. In fact, she wasn't even moving at all. She was completely unconscious.

It couldn't be too late.

He immediately sprang up, pulling her into his arms as quickly as he could.

"Beckett," he said, a sense of urgency in his voice. "Come on. Wake up."

He placed his hands on her shoulders and shook them gently as he spoke, instantly noticing how clammy and cold her skin was beneath his touch. Her head lolled back, jerked around by his shaking, and her eyes remained shut, her chest frighteningly still.

"Damn it, Kate!" he shouted, reaching into his pocket for his cell phone. He had to call 911. He had to get an ambulance here. He had to...

His phone was dead. Of course. It had been submerged in water for several minutes. And now, he had no way to contact anyone. No way to let anyone know that they were stranded here; no way to let anyone know that Kate wasn't breathing...

Kate wasn't breathing.

He had to do something. He had to save her.

Rick shifted his hands underneath her body, gently cradling her head as he lowered her to the ground, laying her flat on her back. She looked so peaceful lying there, her lashes kissing her cheeks and her dark hair surrounding her head like a halo. It was almost as if she were asleep.

Except she wasn't breathing. Her face was blanching, and her lips were starting to turn blue. If he didn't act soon…

"Stay with me, Kate," he murmured, brushing a strand of hair out of her face. The simple action caused an onslaught of memories- Beckett lying on her back, her blood a bright red against the cemetery's green grass; him kneeling over her, just like he was now, begging her to stay with him, because…

He loved her. He loved her, and she had to live.

It couldn't be too late.

He placed his palms carefully against her sternum, his mind racing as he tried to remember what he'd learned in CPR training all those years ago. Chest compressions were done with the heel of his palm- that much he remembered- but how many was he supposed to do? God, why couldn't he remember?

Twenty, he decided. Quickly, he laced his fingers together and began to press down on her chest, rapidly and repeatedly, counting aloud with each compression. The desperation in his voice as he counted matched Beckett's, when she'd given CPR to Coonan as he lay on the precinct floor, a bullet wound in his chest.

A bullet wound just like the one Kate had received from the sniper, just a few short months ago; a wound whose scar lay directly beneath his palms; an eternal reminder of the time she nearly lost her life.

If Kate Beckett could survive a bullet to the heart, she would make it through this. She had to.

As soon as he reached twenty, Rick pinched her nose closed with his right hand as he gently covered her lips with his, blowing air into her mouth. His left hand remained on her chest, and he felt it rise and fall as he breathed for her. After a second breath, he pulled away from her, his eyes darting to her chest, watching for any further motion. But she was still.

Kate still wasn't breathing.

Oh, God.

He moved his hands to her chest again, beginning compressions again, with more vigor than the first time. He had to keep going; he had to keep administering CPR until someone showed up. Because someone was going to come. The boys would find them; they'd bring dry clothes and hot coffee, and why was Kate so cold…

Eighteen. Nineteen. Twenty.

He allowed his hands to linger on her chest for what seemed like an eternity, waiting to feel her chest rise and fall; waiting for her to take a breath. She remained motionless, though; the color continuing to fade from her cheeks as he watched the life drain out of her for the second time this year.

No. This couldn't be happening.

"I can't lose you!" he cried out, anguished, as he placed his left hand under her head, cradling it gently. "Not again…"

Rick leaned over her, positioning his mouth directly over hers. "I love you, Kate," he whispered, his lips brushing against hers; his words breathing life into her body. "I love you."

Almost instantly, she gasped, water spurting from her mouth as she began to cough.

She was alive.

Quickly, Rick pulled her into his arms, sitting her up and patting her back as she continued coughing. Finally, the coughs subsided, and she curled into his chest, letting out a shaky breath as she laid her head on his shoulder, her body weak and frail.

"You're okay," Castle murmured reassuringly, pulling her closer to him. She was shivering now; the cold night air exacerbating the effects of the frigid water they'd been submerged in for so long. She closed her eyes and coughed again, her whole body shaking.

"You're okay," he repeated, gently rubbing her back as he cradled her body against his. "You're safe."

"Castle," she whispered, the effort of speaking causing another fit of coughing to overcome her.

"Shh," he soothed. "Don't talk. It's okay."

"No," Kate said, taking a deep breath. "Castle… I… I love you, too."

Author's note: Thanks to Ellie (thebazilelord) and Jo (fan1bsb97) for sharing their CPR knowledge and reading through this before I published.