Blood and Black Lace is the greatest movie of all time

Blood and Black Lace. "The sight of beauty makes him lose control of himself, so he kills." "Listen here, you little idiot." What a delicious flick this is. Full of luscious, vivid colors, that aspect is reminiscent of the old Batman series (had to be shot with the same film), except extremely dark and violent. The clothing, the colors, the beautiful people, the architecture, the way the film is shot--all beautiful. A total feast for the eyes. 

Gist is that a model for a lux Italian fashion house where everyone is on coke is strangled by a masked killer (obvious visual inspiration for DC's the Question and Rorschach from The Watchmen). When her diary shows up, it turns out everyone has something to hide, and models start turning up dead. Everyone is a suspect, including the fashion house owner (who looks like Julia Fox) and her lover. Also, not to give too much away, the ending is wild. 

If the violence wasn't so over the top, it might be a good movie to trip to, if you are so inclined. But it's too brutal for all that, IMO. For example, of the film, critic Chuck Bowen of Slant Magazine wrote: 

Thematically, Blood and Black Lace offers the giallo an irresolvable obsession with female violation that's simultaneously cruel and heartfelt. Here, the murders are understood to reflect a debasement that suggests a furthering of the debasement of modelling, a suggestion that's literalized by the killer's placement of the bodies in hideous poses [...] This thematic is complicated further by the identity of the killer, who reflects the fashion industry's self-loathing and self-consumption, driven by a mixture of profound self-interest and neurosis that would be enormously influential to the subgenre at large. In a giallo, a woman's worst enemy is often a woman driven to shirk the chains of status quo that shackle her. 

So, yeah, the debasement of women is not really a place I want to go whilst out of my mind. 

This is a must-watch if you want to delve into the world of giallo ("yellow" in Italian) cinema.  Blood and Black Lace is credited as being one of the first of the genre. The film created some of the tropes that giallo is known for. Shit like exaggerated color, killer POV, women getting slapped in the face, extravagant set pieces, red phones, mannequins and harps, and the killer wearing black gloves. 

The word "giallo" comes from Italian crime/thriller novels Il Giallo Mondadori known for their distinctive yellow covers. You can think of the genre as highly stylized blends of murder mysteries and proto slashers. A lot of their DNA comes from Agatha Christie novels that they were just ripping off. If you are familiar with the spaghetti western genre that was coming out of Italy at about the same time, it is similar in that it takes a popular genre and repurposes it with post-war Italian fears and sensibilities whilst upping the sex and violence. 

Directed by one Mario Bava, who repeatedly defied convention with his use of wild, saturated color. In those days, color was used exclusively for comedies and musicals. Thrillers such as this were typically done in black and white. See Diabolique, Night Train, Psycho, The Hitch-hiker, so forth. The use of color is actually integral to the film, which Bava color-codes, linking each character and killing to a specific hue. 

For example, the character of Isabella, whose murder opens the film, wears a red coat and has red fingernail polish. We also keep coming back to her red diary, which survives her and calls back to her killing as a beautiful MacGuffin. It is generally accepted that this is an homage to Edgar Allan Poe's story "The Masque of the Red Death," set in an allegorical series of colored rooms. Bava was highly influential in this regard. Fellow giallo director Dario Argento (Deep Red, Inferno, Suspiria, Tenebrae) also uses vivid pops of color in his wonderful films. For a nice source on the genre, check out the blog The Giallo Files. 

Overall, the film is super fun with great a score with insane use of color. Extremely underappreciated, it created its own genre, which is pretty dope, like Scream did with self-aware horror. Favorite scene is when the roommate puts the diary in her purse and it individually cuts to all the usual suspects staring at the bag, breathing heavy and sweating.