In a rust-blooded river town where foundry whistles once set the sky on fire, a fallen clock tower keeps a secret no one wants to hear again. Two decades apart, two betrayals, and a legend whose gears never stop turning: the Iron Heart of Hartenwell Tower. Some riddles refuse to rust.
As first-year students at Ruston Polytechnic in Forgehaven, Pennsylvania, Elodie Crane and Mara Kessler wanted nothing more than to outpace their pasts with caffeine, welding goggles, and mixtapes that rattled the windows of their beat-up Saturn. But the campus had its own obsessions: a century-old automaton rumored to throb within the clock tower, built by widowed engineer Hester Hartenwell after a foundry blast took her apprentices. The Iron Heart, people whispered, could choose a successor among the women who solved its riddle. The ones who looked hardest tended to die badly. A lab leak. A fall from the tower stairs. A girl found facedown in the lock, pockets stuffed with ball bearings. Aspiring reporter Mara begins recording interviews on a microcassette, chasing patterns through the machine shops and the unofficial after-hours club called the Calipers. Elodie, the quieter of the two, sketches blueprints no one else is allowed to see. The deeper they dig, the hotter the furnace runs, until a night of sparks and screaming steel ends in accusations and a cover-up that tears their friendship clean in half.
Nearly twenty years later, Elodie is living a prize-tied life in Maple Hollow, a tidy development of cul-de-sacs and ornamental pears outside Philadelphia. She has a careful husband, Daniel Pritchard, a careful child, Wren, and a job dressing other people's secrets in tasteful neutrals. Then Mara is found dead in Forgehaven, her drowning called a tragic accident. The week before she died, Mara had mailed Elodie a cast-iron heart the size of a fist, its plates engraved with coordinates and a motto: Ferrum memorat. Iron remembers. In Mara's eerily preserved rowhouse, a metronome ticks all night, the microcassettes hiss with half-finished interviews, and a rust-colored Dodge with mismatched hubcaps idles at the curb. Elodie starts fitting the heart's gears together, realizing the riddle requires the tower's shadow at exactly 3:17 and a key hidden in a blueprint fold no one has touched since 1901. Every turn of the mechanism shakes loose something uglier: patents stolen from students after staged accidents, a professor named Alden Pike whose power outlasted his tenure, an alumni fund fattened on silenced genius.
With her husband discovering the lies she told about Forgehaven and threats sliding into Wren's lunchbox in the form of schematics, Elodie must decide whether to protect the life she built on a foundation of omissions, or open the tower and name the hands that spun death into legacy. Because Mara never stopped hunting the truth, and if the Iron Heart is still beating, then someone has been oiling it all along.
