This film is yet another that has extremely tenuous claims to being a giallo. Such claims are only laid at the very end of the film, when a twist ending reveals that the film we thought we had watched was not in fact the film we saw.
The twist, which rivals that of the later House on the Edge of the Road for credulity-stretching, is one of those wholly unnecessary ones which force you to reassess and reinterpret everything you've just seen, without actually improving the film (c.f. Haute Tension). The film appears to be about a sexually perverted rich man (Philippe Leroy) who fantasizes about torturing and killing a woman, and who seizes his chance to do it for real when one of his regular role-playing prostitutes cancels on him. The victim, a seemingly innocent journalist (Dagmar Lassander) who is invited back to the man's house, turns out (SPOILER!) to be a serial killer, who targets men who like to humiliate women. She has teamed up with the prostitute, who has given her the inside scoop on what to expect, and used this knowledge to ensnare her victim, all the while playing the role of victim herself.
The film works well as a slice of 60s pop-art-infused kitsch, but is an utter failure as a giallo. It's impossible not to be suspicious of Lassander's motives once Leroy fails in his attempted murder, and she almost immediately falls into her arms. The fact that she has done this kind of thing before doesn't make her revenge any more poignant or effective (though is gives the text a quasi-female empowerment edge that might not otherwise have been there). One also has to question how a prostitute who had formerly engaged in role-playing games with Leroy's character would know for sure that he would be incapable of murder when the chance arose, given that all of their interactions were based on pretence.
As I said, the film does have its pop-arty merits, and Stelvio Cipriani's score is brilliantly used throughout. The direction is fairly stylish, and the sets and photography are top-notch. As a giallo, though, it's a dud.
PS It's interesting, and largely, refreshing to note that a film in which a woman is held captive for over half the running time doesn't resort to leering at her body and/or predicament. In fact, Leroy's body is subjected to more leering close-ups than Lassander, which could further the case for this film as a quasi-feminist tract.
PPS The film is known as both The Frightened Woman and The Laughing Woman, the former presumably being used by distributors trying to mask the film's twist, and the latter by distributors who were happy to divulge. It's a matter for debate as to which was the better strategy.