The Murder Secret was apparently 'overseen' by the great Lucio Fulci. I have no idea what that means, but the great director does have a producer's credit so maybe adding his name to it wasn't just a shameless attempt to sell the film (or maybe it was). Anyway, the film is actually directed by Mario Bianchi who you may (but hopefully not!) remember from the likes of A Girl for Satan and Emanuelle in the Country. The film takes on a mystery/Giallo tone and I get the impression that it could have been rather good with better handling, actors and atmosphere. Anyway, the plot focuses on a family that are making the drive see the father's Aunt Martha. They arrive at the rather large house to find that Martha is not there, but will arrive the next morning. Unbeknown to everyone but the father, Martha has until recently been a guest in a mental hospital. The family is invited in by the caretaker to stay the night while they wait for the Aunt to arrive, but soon after they begin being murdered.
The film is rather slow for the first hour and not a great deal happens. I actually have no problem with this in theory as a good build up can only be an asset to a mystery film; but unfortunately this build up can't really be considered good as nothing really happens. Lucio Fulci's "influence" kicks in at about the hour mark when the murders finally start happening, and they're fairly bloody - a decapitation with a chainsaw is a particular highlight. The plot itself isn't bad really, but the characters let it down as not a single one of them is interesting and we really just end up waiting for them to be picked off. The film has no style to speak of and the look of the film is extremely bland - a shame considering that atmosphere tends to be one of the best things about good Italian horror. The dubbing is atrocious also, and the soundtrack is one of the worst I've ever heard in an Italian horror film. It all boils down to a terrible ending, which is a shame because it was starting to look like it might finish well. Still, I don't want to totally condemn to the film; it does have its moments and to be honest I'm a sucker for this sort of stuff. Italian horror fans may find something to like...but I wouldn't recommend going out of your way to find it.