My heartbeat is so steady that sometimes, I don't resemble a human being at all. The fluctuations in my heart rate are very small even though I might be sleeping, suffering from a fever, or losing too much blood.

When I'm 18 years old, the Ziegler family admits me into a rehabilitation center. My new home is now a temperature-controlled intensive unit located on the top floor.

Oh, Aiden Ziegler doesn't love me at all. It's merely because the one and only artificial heart present in this world—and also in his chest—needs to be fine-tuned with my own heartbeat as its primary frequency.

If my heartbeat is steady, he gets to live. If not, he dies.

Three months ago, a nurse accidentally took off one of the monitoring pads on my chest. Five minutes later, Aiden, who was ten thousand miles away, went through a temporary crash where his heart stopped.

The next day, the third-party medical company filed for bankruptcy. Everyone who was involved in this incident got banned by the medical world.

Because of that incident, all of the sounds get eradicated from the top floor. Even the elevator's chimes get muted when it reaches the top floor of the rehab center.

Everything changes when Aiden flies to Iropa. That's when his fiancee, Mandy Sutherland, takes over the rehab center.

As she flips through my medical bill of nine figures, she sneers at me.

"So, the Zieglers are basically sustaining a loser who does nothing but gasps for breath while lying in bed, huh?"

After that, Mandy tears off the monitoring pads and unplugs the sync line. Then, she forces me to get on a treadmill.

"That'll be a six-mile run for you. You can forget about returning to the top floor if you can't finish the run."

As I grip the handrails tightly, I can feel my heart rate turning erratic for the first time ever. It feels as though my heart is about to burst out of my chest.

As soon as the alarm goes off, Mandy turns it off immediately.

What she doesn't know is that Aiden's artificial heart has already gone crazy, just like mine, while he's stuck in a place that's 12 time zones away.

The treadmill went from a slow walk to a sprint in three seconds. Two security guards grabbed me by the arms and pinned me down against the handrails. The spots on my chest where they'd just ripped off the monitoring pads still burned.

"Turn it up," Mandy Sutherland said.

She stood outside the glass wall, her arms crossed as she watched us.

A nurse was beside her. Her face went pale, and she said, "Ms. Sutherland, she can't do intense exercise—"

"The Ziegler family spends nine figures a year to keep that heart beating. I want to see how precious it really is," Mandy said nonchalantly.

The speed jumped to ten. My knees smashed against the edge of the belt, and my vision went black around the edges.

The alarms blared. [Abnormal heart rate detected. Primary frequency unstable. Remote sync risk rising.]

I grabbed hold of the handrails so tightly that my knuckles turned white. My words came out in chopped bursts between ragged breaths.

"Don't… don't shut down… the sync line…"

Mandy walked in and bent down so we were face to face. "Still acting, huh?"

She slapped a thick stack of annual invoices onto my face. Climate-controlled chamber maintenance, medical team salaries, imported medication, a dedicated server farm… Every number on the page was big enough to kill.

She picked one up and read, "130 million dollars a year. What value have you ever created for the Ziegler family? Nothing. All you do is lie there and breathe."

Cold sweat ran down my temples, and my heart felt like it was being squeezed tighter by the second.

There was nothing wrong with my heart. The real problem here was that the second my heart rate spiraled out of control, that artificial heart 12 time zones away in Aiden Ziegler's chest would go with it.

I rasped, "Ms. Sutherland… it's not too late… for you to stop this now…"

Mandy's hand cracked across my face. My mouth filled with the metallic taste of blood.

The nurse, Noelle Tate, rushed forward, grabbing spare monitoring pads. "Ms. Lane can't run anymore!"

With one look from Mandy, the security guards yanked Noelle back. The monitoring pads went straight into the trash.

"You're suspended. One more word, and you can forget about working in medicine ever again," Mandy said briskly.

Noelle froze where she stood, too scared to move.

By the time the treadmill finally stopped, my legs gave out, and I dropped to my knees. A heavy ache kept slamming through my chest, harder each time, but the shrieking alarms cut off in an instant.

Mandy had killed the display. The world went quiet. All that was left was my uneven breathing.

She glanced up in the direction of the top floor where I lived, then suddenly smiled. "Search her monitoring suite. I want to see what exactly the Ziegler family's money has been keeping alive."

Two lawyers and the security guards headed upstairs. By the time I was dragged back to the top floor, my room looked like a crime scene. The climate-controlled pod was cracked open, and backup medication was scattered all over the floor. Even the small safe by my bed had been pried open.

A lawyer walked over to Mandy with a few documents. "Ms. Sutherland, we found these."

She took the papers, skimmed them, and slowly smiled. "Rebate agreement with an equipment supplier."

She flipped to a few more pages. "Offshore transfer records."

She looked back at me, her eyes shining with triumphant satisfaction. "Anything you want to say for yourself, Geraldine?"

I stared at the documents. For a moment, I really wanted to laugh. None of those things were mine, but I could barely even stand up straight now, let alone defend myself.

Mandy was already announcing the verdict. "You colluded with medical equipment vendors to siphon off Ziegler Group's medical resources, and you faked your condition to steal special funding."

She slapped the papers against my face. "Effective immediately, Geraldine Lane is stripped of top-floor intensive monitoring privileges. Transfer her to a standard observation room."

I jerked my head up. "You can't do that."

The top-tier sync environment couldn't be broken. The climate control, the soundproofing, the dedicated servers, and the monitoring pads—every single piece mattered.

Mandy just assumed she'd finally found my weak spot.

"What's wrong? Can't live without your penthouse suite?" She leaned down and gripped my chin. "Then you can just drop dead."

I was being dragged out of the room when the rehab center's main control wall suddenly exploded in red alerts.

[Primary frequency lost. Remote artificial heart sync failure. Emergency contact: Aiden Ziegler.]

Mandy glanced at the wall. Then, without even batting an eye, she reached out and shut down the entire display with a quick flip of a switch.

At the same time, Aiden was bent over a table in a conference room in Iropa, signing a merger agreement. The tip of his fountain pen had just touched the paper when it slashed hard across the page.

A second later, the artificial heart in his chest let out a piercing alarm.

The regular observation room was on the third floor of the rehab center. There were no soundproof walls or temperature control.

I curled up on the hospital bed. My fingers dug into the sheets, my chest feeling so tight that I couldn't make a sound.

The door flew open. Quentin Stark rushed in, his white coat hanging open, every button undone. He was Aiden's attending physician and the only person in the entire center who knew the whole truth.

The moment he saw the empty patches on my chest where the monitoring pads were supposed to be, his face went completely white. He spat, "Who said you could rip off her monitoring pads?"

Mandy was sitting on the couch, flipping through my chart. She didn't even look up.

"Dr. Stark, I'm the acting director of this center." She pushed a board authorization letter onto the table. "While Aiden is away, this facility answers to me."

Quentin didn't spare it a glance. He came straight toward me, saying, "Geraldine can't stay here."

He reached out to reconnect my portable synchronizer, but two security guards stepped in front of him.

"Move!" Quentin barked.

Mandy stood up. "Why are you so protective of her? She's under suspicion for medical fraud, and you're guarding her even more fiercely than Aiden does."

He clenched his jaw so hard that it trembled. He knew that he couldn't tell her the truth. Aiden's artificial heart relied on the calibration of my primary frequency. It was the Ziegler family's highest-level secret. If that ever got out, Aiden would instantly become a walking target for the entire capital market.

All Quentin could do was force out hoarsely, "Her sync can't be interrupted. If something happens to her, Mr. Ziegler will die."

Mandy laughed. "So if anything happens to Geraldine, Aiden's life will be in danger?"

She walked to my bedside and looked down at me. "You really are something. Even Dr. Stark is willing to lie for you."

I opened my mouth, but the pain in my chest was so overwhelming that I couldn't squeeze out a single word.

The last traces of color drained from Quentin's face. "Ms. Sutherland, this is my last warning. If you stop now, I can still fix this."

"Fix this?" Mandy's smile turned icy. "What needs fixing is the money that she's scammed the center out of over the years."

She pointed at Quentin. "Take his badge."

The security guards grabbed him and dragged him toward the door.

"Mandy Sutherland, you're going to regret this!" he shouted.

She ignored him and turned to the head of the tech department. "Is the backup sync server on the top floor still running?"

He instantly blanched. "Ms. Sutherland, that can't be shut down. It's tied to Mr. Ziegler's remote artificial heart calibration parameters. If you cut that—"

"Aiden again." She cut him off, the look in her eyes darkening with every passing second. "Every single one of you is using him to pressure me."

She picked up a walkie-talkie. "Shut it off."

The tech head lunged for her, but a guard kicked him to the floor.

A few minutes later, the entire rehab center flickered into darkness for a split second. The monitor by my bed screeched with static as the heart-rate line went haywire. I clutched my chest and arched off the mattress, my whole body convulsing.

Out in the hallway, Quentin was pinned to the floor, the veins at his temples bulging. "Mandy, he'll die! Aiden really will die!"

Mandy stood at the foot of my bed, motionless as she watched me seize and twitch. "He can die as I watch, then."

Her phone rang. An encrypted number flashed on the screen, labeled with a single word—Iropa.

She answered.

Aiden's assistant, Sam Grant, sounded out of control. "Ms. Sutherland, Mr. Ziegler suddenly collapsed in the middle of a meeting. His artificial heart has gone into emergency protection mode! Did something happen at the rehab center?"

For a split second, Mandy's expression shifted. She looked down at me, taking in the cold sweat that drenched my hairline and my ragged breathing.

Whatever flicker of doubt she'd felt vanished from her eyes, replaced by open mockery. "This is a whole performance, isn't it?"

Sam was still shouting on the other end of the line. "Ms. Sutherland? Can you hear me?"

She hung up, turned off her phone, and tossed it back into her bag. "Aiden has an entire Iropan medical team with him. He doesn't need some con artist to save his life."

I lay on the cold, hard bed and listened to my heartbeat, feeling my heart sink with every brutal thud.

By the time I was wheeled into the exam room, my fingers were shaking uncontrollably. The electrode pads were ice-cold against my skin; the sharp chill reached my bones. The lines on the monitor were still a mess.

Quentin was restrained out in the hallway. His white coat was smeared with dust, and his gaze was fixed on me. "Geraldine, hang in there."

I tried to force a smile but couldn't manage it. It felt like a thousand thin wires were cinched around my chest, tightening ring by ring.

The rehab center's director rushed in, his hair completely rumpled. He shoved a tablet in front of Mandy. On the screen were two sets of data. One was my own heart-rate waveform, and the other was the remote output from Aiden's artificial heart. The timestamps, the peaks, the instability pattern—every last detail was a perfect match.

He said shakily, "From the moment you removed Geraldine's monitoring pads, Mr. Ziegler's readings started going haywire. When you cut off the backup server, that's when he blacked out for the first time.

"Right now, Geraldine's heart rate is still in constant arrhythmia. Mr. Ziegler's artificial heart has already entered a state of critical risk."

For a second, Mandy's expression darkened. Then, she smiled mockingly. "Data can be faked."

The director was taken aback.

Mandy tossed the tablet onto the table. "This entire rehab center is staffed with Aiden's people. It'd only take a word from him for all of you to help Geraldine spin a lie, wouldn't it?"

The director cried anxiously, "Ms. Sutherland, we're talking about human lives!"

"That's exactly why I intend to get to the bottom of this." Mandy turned and motioned for the lawyer to hand something over. Then, she shoved a pen into my hand. "Sign this."

I looked down at the document. It read, "Voluntary Statement of Admission to Medical Fraud and Misappropriation of Special Medical Resources."

According to it, I had been faking my illness for years, colluding with doctors at the rehab center to scam the Ziegler family's medical resources.

I let out a hoarse laugh. My throat felt like it had been scraped raw with sandpaper. I croaked, "Mandy Sutherland."

She stared straight at me.

I lifted my head and enunciated, "You're not punishing me. You're personally destroying Aiden's heart."

Her face frosted over. "Threatening me, are you?"

My fingers shook so hard around the pen that I could barely hold on. "I'm not threatening you. I'm trying to save his life."

Mandy suddenly leaned down and clamped a hand around my wrist, gripping it viciously. The pen tip ripped across the paper, slicing through it and into the pad of my finger.

"Save him? Who do you think you are?" She sneered. "What Aiden needs is a top-tier medical team and the most advanced artificial heart technology in the world. He doesn't need some piece of trash picked up from an orphanage."

She let go of me and turned to a nurse. "Give her a stimulant."

The nurse turned deathly pale. She didn't dare move.

The director hurried forward to stop her. "You can't do that! Her primary frequency is already in chaos. If you inject a stimulant, it'll trigger complete cardiac collapse!"

Mandy picked up the syringe and walked over to me. She said icily, "You're good at putting on an act, aren't you? Show me just how steady your heartbeat really is, then."

I went rigid the moment the needle pierced my vein. The icy medication flooded my bloodstream. A few seconds later, it felt like someone had grabbed my heart and hurled it into a vat of boiling oil.

Thump. Thump. Thump.

I could hear my own heartbeat losing its rhythm, pounding so wildly that it felt like it was going to smash through my ribs. The monitor let out a piercing shriek.

The director lunged toward me, but the security guards tackled him. Out in the hallway, Quentin struggled against the guards restraining him, his eyes bloodshot. "Mandy Sutherland, you're insane!"

I slid off the exam chair. My knees slammed onto the floor, but I couldn't feel the pain. My vision kept going dark around the edges.

In the haze, I suddenly remembered the first time I'd met Aiden all those years ago. He'd been in a wheelchair, his face as white as a sheet and his chest covered in tubes and wires.

The doctor said my heartbeat could keep him alive, but all he did was lower his head and ask me, "Will you do it?"

I'd been so young then. I'd asked him, "What if I say I won't?"

He'd been silent for a long time before finally saying, "Then forget it."

But in the end, I'd stayed. Because that day, even when he'd been on the brink of death, he hadn't forced me to do anything.

And now, someone else was doing the job for him. They were forcing me to die.

…

At the same time, in an emergency room in Iropa, Aiden briefly opened his eyes. The doctor was about to fit an oxygen mask over his face when he shoved it aside.

His chest heaved violently. The alarm from the artificial heart was shrill enough to split eardrums.

Sam leaned over him. "Mr. Ziegler, you can't move!"

Aiden's voice was hoarse. "Prep the jet. We're going home."