This week on “Picture Perfect,” as the shadows lengthen, we revisit the world of film noir, a genre notoriously slippery to define, but easy to know when you see it – with its long shadows and moral ambiguities; cock-eyed camera angles and snappy repartee; isolation and innuendo. It’s a genre where a pair of gams is an invitation to the gallows; where a man’s best friend – and sometimes his worst enemy – is his Colt .38; where only cigarettes and bourbon can ease the pain.

The labyrinthine mystery at the heart of “The Big Sleep” (1946) is so disorienting, even the book’s author, Raymond Chandler, couldn’t tell whodunit. Who cares? Humphrey Bogart and Lauren Bacall get some more steamy dialogue to satisfy fans of “To Have and Have Not,” and there’s plenty of Bogey pounding the pavement and tossing off tart one-liners in pursuit of the truth. But my favorite scene involves Dorothy Malone, who runs the hottest bookstore in town.

Whenever there are gallows to be built or gangsters to be beaten, Warner Brothers could be counted on to assign Max Steiner.

“Chinatown” (1974) is one of the best of the neo-noirs of the 1970s. This time, Jack Nicholson plays private dick J.J. Gittes, who takes on a seemingly routine case that begins to spiral out of control. When producer Robert Evans rejected Philip Lambro’s original score, Jerry Goldsmith stepped in as a last-minute replacement. The composer was hired with the understanding that he had only ten days to write and record new music. For his effort, Goldsmith received an Academy Award nomination.

The Coen Brothers clearly love noir, from their first feature, “Blood Simple,” to their Academy Award winners, “Fargo” and “No Country for Old Men,” to their absurdly entertaining reimagining of “The Big Sleep,” “The Big Lebowski.” “Miller’s Crossing” (1990) was one of the more underappreciated of these. The film follows the well-worn device of an anti-hero playing two sides off of one another, until he is the last one standing – shades of Dashiell Hammett’s “Red Harvest,” with a healthy dose of “The Glass Key” thrown in, for good measure. The Irish-inflected score is by Coen regular Carter Burwell.

Before he became stereotyped as a composer for epic films like “Ben-Hur,” “King of Kings” and “El Cid,” Miklós Rózsa was the king of noir, providing scores for genre classics such as “Double Indemnity” and “The Strange Love of Martha Ivers.” We’ll hear a suite assembled from three such projects: “Brute Force” (1947), a hard-hitting prison drama, starring Burt Lancaster as a desperate inmate and a contemptible Hume Cronyn as a sadistic guard; “The Killers” (1946), also starring Lancaster as a marked boxer; and “The Naked City” (1948), with Barry Fitzgerald leading a police investigation into the murder of a young model. The suite is titled “Background to Violence.”

Put on your rumpled linen suit, draw the Venetian blinds, and play the sap for nobody this week. It’s film noir in the gritty city, on “Picture Perfect,” music for the movies, this Saturday evening at 6:00 EST, on WWFM – The Classical Network and at wwfm.org.

The theatrical trailer for “Brute Force”:

PHOTO: Bogart and Malone talk literature