Police inspector, Capuana (Granger) is brought on a homicide case of a married woman found with multiple stab wounds and scandalous photos spread around her corpse. However, his attempts to investigate are stifled by the woman being a general's wife. When another woman is killed in the exact same way, Capuana soon learns that both victims were apart of the same circle of upper class women married to prominent men and a Serial Killer is punishing them for being unfaithful.
So Sweet, So Dead contains examples of:
- And Starring: "Also starring Susan Scott"
- Attempted Suicide: Lilly's husband tried to kill himself, but it failed and now the lower half of his body doesn't work anymore.
- Bury Your Disabled: Due to needing crutches to move around, Lilly's husband ends up taking a deadly fall.
- Coat, Hat, Mask: The killer disguises themselves in the classic giallo garb, but with an added black stocking over their face.
- Downer Ending: The murderer is dead, but Capuana is a broken man due to his wife's infidelity and the scandal will likely damage his reputation. Not to mention, our protagonist just sat back and watched as his wife was killed.
- Newspaper Backstory: Near the end, Capuana finds a cut-out article that reveals the event that lead to the killer's Start of Darkness.
- No Full Name Given: Too many.
- The protagonist is only ever called Inspector Capuana.
- Professor Casali and his colleague, Gastone.
- All the victims, aside from Franca and Barbara.
- The victims' paramours.
- Bettina's boyfriend, Piero.
- Rossella and Giannina
- No Name Given: Lilly's Husband, the suspect that confesses, and many of the reporters that respond to the press conference.
- Averted with Floriana. While she's only credited as "First Victim", the other wives mention her name when they're discussing the murders while getting massages.
- Red Herring:
- The mortician, Gastone prides himself in his work of sealing up wounds, likes taking pictures of the victims' naked bodies, has a darkroom where he develops the photos, and at one point hides a switchblade when Capuana visits his house. Despite all this, he's not the killer.
- Prior to the fourth victim's murder, her husband is shown stalking her at the train station. It's later discovered that he was just saying goodbye to her and during her murder, he was playing poker with the police commissioner.
- Justified. Capuana, knowing the murderer has an ego, decides to arrange the false confession and arrest of a psychotic man, thinking that it would insult them. It works, but too well.
- The Reveal: Two.
- Inspector Capuana's wife, Barbara, has been cheating on him.
- The killer is the city's coroner, Professor Casali, who was murdering adulterous women because his own wife cheated on him before the movie and got killed in a car accident while going to elope with her paramour.
- Sinister Switchblade: The killer carries a switchblade and uses it to carry out their murders.
- Staircase Tumble: After Lilly is killed, her husband tries to go down the stairs on crutches, but he slips on the first step and is sent tumbling to his death.
