The classic whodunit wrangles a group of suspects into a space together, gives each of them a possible motive for committing a murder, and then brings in a high-toned investigator to sort it all out. A few twists and possibly another murder later, it's finally determined that Colonel Mustard did it with a lead pipe in the conservatory. The exceedingly clever 1946 whodunit Green For Danger starts out playing by the rules: A seemingly motiveless murder has been committed during minor surgery at a rural English hospital, and a witness is killed shortly thereafter. Alastair Sim shows up as Scotland Yard's best, so brimming with confidence that he generously allows his five suspects "30 seconds to think up an alibi." But the film's sly masterstroke is that it slowly turns on the arrogant, self-satisfied inspector.

Before Sim arrives, writer-director Sidney Gilliat, working from Christianna Brand's novel, establishes a heady atmosphere of anxiousness, suspicion, and surprising erotic charge. Set during the Nazi air raids, which layer several scenes with anticipatory dread, the film opens with a mailman trapped under the rubble of a razed post office. His injuries require surgery that seems non-life-threatening, but he dies on the operating table while anesthetics are being administered. A nurse on hand announces that she knows who was responsible for the fatality, but she falls victim to a surgeon's knife. When Sim comes to clean up, he seems to have everyone pegged, but he knows less than it appears.

Having written screenplays for Alfred Hitchcock's The Lady Vanishes and Jamaica Inn, on top of a formidable list of credits, Gilliat understands the mechanisms of suspense inside and out, which lets him tweak convention while still serving the genre satisfactorily. For what's essentially a drawing-room mystery, Gilliat breaks out a few surprisingly cinematic sequences, especially the expressive second murder, which plays beautifully with light and shadow. But the movie belongs to Sim, whose preening omniscience is revealed to be tragically, hilariously bunk.

Key features: Solid commentary by film and music historian Bruce Eder, a short interview with British film historian Geoff Brown, and liner notes that include a telling statement by Gilliat.