X the Unknown (1956)

Conceived as a sequel to the first Quatermass film but changed due to permissions denied, X nevertheless manages to feel like it still belongs in the series. An unexpected radiation emission is discovered during a routine military training exercise in a field in Scotland. As the danger level creeps higher the solders seek the help of a scientist, Dr. Adam Royston.
As usual in budget-tight productions the tension is initially achieved by not showing the creature. Instead, the kills are shown, a few of which are gruesome for the period. But it's the strong performances of actors Dean Jagger and Leo McKern that really make the film memorable, not its devices.
Hammer regular Michael Ripper pops up occasionally as a Sergeant.

3½ muddy crevices out of 5