You don’t have to seek out classic films at museums or small cinemas anymore. Nowadays they are accessible to anyone whose cable package includes the movie channel TCM. And many great and not-great older movies have been issued on DVD.

With the easy availability of old film, why would anyone launch a vintage film series at a public venue in 2008? “It’s for the shared experience,” explains Dan Guenzel, co-founder of the Focus Film Society. “If you watch a Harold Lloyd comedy by yourself on DVD, you smile. If you see it in a theater with other people, you are shaking with laughter. It’s an entirely different experience.”

Hank Landa is the other half of the Focus Film Society, which screens older movies every second and fourth Saturday at the Plymouth Church near the Downer Theatre on Milwaukee’s East Side. A familiar name to longtime local cin�astes, Landa ran a revival house in Bay View, the Gallery Cinema, from 1981 through 1990. Back in the ’60s, he was involved in film societies at UW-Madison, then a thriving center of cinema culture. Film writers Richard Schickel, Michael Wilmington and Patrick McGilligan were among the students on campus who would contribute to our understanding of the cinema. For Landa, the Focus Film Society (FFM) is a return to his life’s avocation.

FFM, which debuted last month, is programming a strong lineup of familiar and unfamiliar titles. Next up is Green for Danger (1946), a superb British crime-thriller from a time when U.K. cinema emerged with renewed energy after enduring the blitz of World War II.

Green for Danger is set during the second to last year of the war in a hospital near London. Air raid sirens and noisy German rocket bombs provide the sonic backdrop.

Just after delivering the hospital’s mail, the postman is injured by an exploding bomb. His suspicious death while undergoing surgery triggers the murder of a nurse who may know too much. Scotland Yard dispatches Inspector Cockrill (Alastair Sim) to clear up the case.

Written and directed by one-time Hitchcock collaborator Sidney Gilliat, Green for Danger is a twisty mystery with many surprises. It’s also a subversive satire of authority figures. The hospital’s administrator is the sort of priggish drone found nowadays in academia and human resources departments. He banished the word “waste” from garbage cans and replaced it with “salvage” to promote positive thinking among the staff.

More dangerous, because he has the power to arrest, is the inspector. Cockrill, a sniggering and arrogant man with an alarming smile, plays with his suspects like an emotional sadist. The psychological unease caused by the Nazi rocket bombs is amplified in the hospital’s close, tense quarters by Cockrill’s campaign of intimidation against the staff.

Like the country manor of an Agatha Christie story, the hospital provides a closed system with a fixed number of suspects. Everyone has a motive in the pressure zone of a wartime casualty ward, where passions can erupt between surgeons and nurses and the human heart twists itself in knots.

Green for Danger is sly and witty, beautifully filmed in lustrous black and white and bathed in deep pools of shadow. It was shown months ago on TCM but has rarely, if ever, been screened locally. Seeing it on the big screen is a treat for anyone interested in 1940s cinema and classic British mysteries.

March 8, 7:30 p.m., at Plymouth Church, 2717 E. Hampshire Ave. Admission is $3 for adults and free for children accompanied by adults.