Dorin looks like a man assembled from workshop leftovers: compact, square-shouldered, and permanently dusted with fine gray grit. He moves in quick, economical starts, then stops so abruptly that his coat keeps swaying after him. His palms are roughened by wire, gears, and hot glass; tiny brass filings cling around his nails. He smells strongly of bitter orange peel and scorched rosemary, a scent he notices only when someone else mentions it. Unexpectedly for a meticulous scientist, he keeps a tiny, carefully folded paper crane tucked behind one ear.

Dorin is generous with his time but guarded with his trust. He jokes freely when a device works, then turns prickly if someone calls its success luck. In calm company he is patient and curious; under pressure he becomes terse, precise, and so absorbed in the problem that he may forget the people waiting for him. He wants to be brave, yet resents being treated as a hero.

Dorin grew up repairing water clocks and mill gears for families who could not afford replacements. His first great experiment was a glass instrument that could identify impurities in well water by the way a drop bent light. It exposed a mine's poison runoff, but the town council dismissed the result as impossible. Years later, during a flood, Dorin used a rough version of the device to locate a buried spring and guide trapped miners to safety. His sister, Ildiko, helped carry the instrument through the tunnels and still insists he owes her a proper apology for risking both their lives. Now he works in a cramped upper room above the old sluice works, investigating strange pulses beneath the town's reservoirs. He trades notes with a practical-minded physician, Oda, and is being pressured by quarry owner Bence to certify a suspicious new pump as safe. The pump's rhythm matches the signal his old glass instrument once detected in the poisoned mine.