"It's just in me," Albert Pierrepoint confesses, the look on his face somewhere between shame and relief. "Always knew it would come out someday." Pierrepoint, like his father before him, was an executioner for the British government, and a good one—between 1932 and 1956, he executed an estimated 450 men and women. Here, in Pierrepoint: The Last Hangman, a drama based on Pierrepoint's life, a haunted look never quite leaves the man's eyes as he briskly, methodically sizes up the condemned, ignoring their pleading whimpers before binding together their wrists and legs, fitting a thin white hood over their heads, securing a thick rope around their necks, and slamming home a lever that drops the floor out from under them. Going about his business, Pierrepoint is hardly kind, but nor is he a monster: He possesses a sort of coldly respectful compassion as he goes about his task, working effectively and sternly, like an accountant hurrying to tally a stack of tax forms.

Outside of the generic prisons in which he works, Pierrepoint is normal—charming, even—delivering groceries, going to the movies with his wife (Juliet Stevenson), and singing songs with a friend in the local pub. He is earnest, and honest, and under no delusions about the nature of his occupation—whether he's pouring a pint or tightening a noose, he nevertheless takes pride in a "professional job, well done."

With his potato-shaped face, neatly parted hair, and weak chin, British character actor Timothy Spall doesn't look like an executioner—yet he is utterly and disconcertingly adept at playing the complex and challenging Pierrepoint. Spall's troubled gaze is a stark contrast to his determined stance and practiced, well-oiled motions; though we see Pierrepoint grimly carry out a good number of executions, one never gets the sense that he is anything less than human—though at times he endeavors, and is required, to set aside his humanity. Pierrepoint follows the man through his career, beginning with his first job interview and ending with his decision, decades later, to quit, after facing several unthinkable challenges. Toward its final moments—as Pierrepoint grapples with an unimaginably heavy conscience, unwanted fame, and the jeers of protestors—the film struggles a bit, straying from its subtler earlier scenes, which are strongly anchored by Spall's magnetic performance. But that's a small blemish on an otherwise gripping film—one that examines a man in such intimate and jarring detail that, no matter how much one might like to, it's nearly impossible to look away.