the glass tomb (1955)

aka The Glass Cage.
"It takes very little to make people happy these days - only money."
'Pel' (John Ireland) is a carnival barker who comes up with a new scheme to make some money. Backed by bookie Tony Lewis (Sid James), he persuades professional faster Sapolio (Eric Pohlmann), to try and to break his world record of 65 days without food. Pel then builds a glass cage where the paying public can view the event. All looks good, but when Sapolio throws a party a woman in an apartment upstairs is murdered. Tony is suspected when it is revealed that he was the girl's ex-boyfriend and she was trying to blackmail him. Then it's revealed that Sapolio may have glimpsed the murderer. This obviously marks him out as a target for the real killer.
Another of Hammers quota quickie, this one being for the most part a run of the mill noir, due in part to the fact that we know the killer from the off, which takes much of the suspense out of the equasion.