Filmed science fiction generally comes in two flavors: British, which has a unique and distinctive character, and everything else. British SF relies heavily on mood, atmosphere and tension, owing as much to Orson Welles as to H.G. Wells. The emphasis is not on startling visuals but on startling concepts. A good British science fiction film could almost take place entirely in a drawing room (and bad ones sometimes do).

Quatermass and the Pit--released in America as Five Million Years to Earth--is an archetype of the genre. The third and best in the Hammer Films trilogy of Quatermass films (which were based on three successful BBC series that aired from 1953 to 1958), Quatermass and the Pit develops the shocking idea that, far from being in danger of invasion, Earth was invaded long ago--only it wasn't the planet that was colonized, it was the minds of humanity. The denouement ends the action but not the horror of what viewers learn about themselves. As Barbara Judd says, "We are the Martians now."

This film--and the series called Quatermass and the Pit that it follows closely--are both excellently written (by Nigel Kneale) and masterfully evocative. Together they had a profound influence on British science fiction. For example, Doctor Who soon began featuring an adversarial Doctor/Brigadier dynamic strongly reminiscent of Quatermass and Breen.

Quatermass and the Pit is a compelling example of how an innovative story, strong acting, and powerful directing can obviate the need for spectacle. After all, science fiction was invented to challenge the mind, not the eye.