Heartbeat unlocks secrets in darkness, revealing hidden truths and unspoken emotions.

Chapter 1: The Unmarked Envelope

On her way home, forensic accountant Mira finds a plain white envelope slipped under her door. Inside: a single Polaroid of her standing in a dark alley—taken last night. No sender. No note.

Chapter 2: Shadows at Dawn

At dawn, Mira’s apartment camera glitches on every playback—but one frame shows a blurred figure standing behind her as she slept. Her pulse races when she recognizes the coat: the same one her missing brother, Arun, always wore.

Chapter 3: The Code in Crimson

That afternoon, Mira discovers Arun’s old journal hidden in her desk. A final entry describes a secret cabal called ‘The Bloodline’. It ends with a cryptic crossword clue smeared in dried red ink. She solves it: ‘Meet me where the river runs uphill.’

Chapter 4: Midnight on the Rooftop

At the derelict river pump station, Mira climbs to the rooftop under a sliver of moon. A lone lantern swings in the wind. ‘Arun?’ she calls—only to watch the lantern drop and shatter, plunging her into darkness.

Chapter 5: The Betrayer’s Mask

A voice whispers, ‘You shouldn’t have come alone.’ Mira fumbles for her flashlight and finds Captain Troy—her trusted police friend—handing her Arun’s blood-stained cufflink. “He uncovered something worth killing for,” he says, eyes cold.

Chapter 6: The Hidden Chamber

Troy forces her through a hidden hatch beneath the station. In a candlelit grotto, walls pulse with carved symbols that match her journal. At the center, a locked iron chest: inside, Arun’s final message scrawled in dust—“I’m already inside.”

Chapter 7: Race Against the Tide

Outside, the river pumps roar to life, water churning toward the grotto. As the chamber fills, Mira scrambles to decode the lock: The last crossword answer—“heartbeat.” The lid clicks open, but only seconds remain.

Chapter 8: The Final Pulse

Inside the chest lies Arun—alive but shackled, his pulse faint. Mira slams the chest closed to keep water out, breaks his chains, and they escape as the grotto floods. On the rooftop, they turn to watch the station collapse—and see Troy’s silhouette disappearing into the night, clutching one final Polaroid: of Mira, smiling.