In Spain it appears that ladies keep their telephones in the shower and, when answering the door, have time only to put on a pair of shoes, but not a pair of grundies. Welcome to Death Haunts Monica, an old school giallo (the kind that involves a rich person and loads of untrustworthy people trying to get their money) that has an mid-seventies giallo mindset (loads and loads and loads of nudity).
Monica herself is a rich lady who is married to and stressed out by playboy Jean Sorel, who has used her money to set up a successful company along with friend Arturo (who is also ex-boyfriend of Monica) and Elena, who tells Monica that Jean is having an affair with Eve, who is also Elena's lover. Jean also has a bit of a dodgy past and that comes back to haunt him in the form of Diego, a man who tries to blackmail Jean and discovers it's really Monica who is holding the purse strings.
That's about as much plot as I'm willing to give away as this film relies on its many twists and turns for impact, and as it's looking back towards those late-sixties gialli (like Umberto Lenzi's Paranoia) it wouldn't be fair to spoil anything else that happens. The seventies archetypal black-gloved killer does show up eventually, but even then things aren't so straightforward.
This is a fine example of the genre with an almost complete lack of gore, although every single actress gets naked (and many others do to, just for the sake of it). Jean Sorel has barely aged a day since the last film I watched him in.