When the glamorous model "Isabella" is found murdered, "Insp. Silvestri" (Thomas Reiner) is drafted in to investigate. Pretty quickly he discovers, as do we, that she kept a diary and it now becomes distinctly dangerous for anyone who has handled this book as the masked killer seems hell bent on retrieving it. There are suspects a-plenty for the killings, and an intriguing sub-lot between a penniless Marquis (Franco Ressel) being blackmailed for an alibi by the boyfriend of one of the deceased, makes the main plot a little more puzzling too. It packs quite a lot into ninety minutes and the story is peppered with red herrings but not in an Agatha Christie fashion. They are more plausible, the characterisations malevolent, duplicitous and back-stabbing and for much of this, we really have no idea who is committing these heinous crimes, nor why. The score is left in the reliable hands of Carlo Rustichelli and though the dialogue isn't that bad, it is this that works well to create a sense of menace - and mischief, as the investigation reaches it's denouement. Tangentially, it takes a swipe or two at the rather insincere worlds of modelling and fashion in general, and is easily as good as the best horror thrillers to emanate from Hammer. Despite the whole thing having something of an episode of "Columbo" to it, it's still worth a watch.
