Philandering Giorgio, played by Jorge Hill Acosta y Lara, AKA George Hilton (AAKA the man born to play such roles), chances upon a killer disposing a corpse in a river in the dead of night. Thinking quickly, he devises a plan which will simultaneously rid himself of his dead-weight wife, and solve his ever-increasing financial woes-blackmail the killer into offing his missus. However, neither he nor the killer had likely banked on a couple of star-crossed lovers stealing the car whose trunk houses Mrs Giorgio's corpse. And the killer, who tracks down the lovers with mostly-remarkable alacrity, had almost certainly not banked on the male lover bringing the ditziest woman in the world back to their coastal hideaway, necessitating the killer to kill again again. And Giogio definitely certainly didn't bank on stumbling across his wife's corpse in the back of a car parked right outside his house. Although even still he should probably have dealt with the discovery in a more level-headed manner. But hindsight is 20-20, and all that.
This is a strange film, obviously shot on an extremely low budget, with a very small cast and few locations. It is a departure from standard giallo fare, which comes as no surprise given Luigi Cozzi's cinephilia. It's essentially the classic 'getting pulled over by the police with a body in the trunk of a car' scenario stretched to breaking point, possibly inspired by Hitchcock's then-recent Frenzy. Its departures from giallo norms are legion, although there is some crossover-the soundtrack, for one, sounds extremely modern even today, and there is an investigation of sorts, even if the police inspector is far from a central character (but given the paucity of same, he's still about 4th lead).
The killer, played by Antoine Saint-John, AKA Max Schweik from The Beyond, has a very creepy face, which is no doubt why he was cast (it's difficult to know for sure whether-as seems likely-he was an extremely limited actor, or just playing a part which didn't call for any nuance of performance). Sporting a permanent sheen of sweat, he looks like a skeleton hungry for the meaty flesh of women. And this is a predilection shared by the film (one could generously argue that 'film' should be replaced with 'marketplace' there), particularly in a bizarre late scene which cross cuts between a lovemaking scene between the male car thief and the stranded motorist he picks up, and a harrowing rape inflicted upon the female thief by the killer.
This scene is probably intended to contrast tender love with the ugly flipside of sex, but doesn't really work because the 'tender love' scene a) involves a guy who's cheating on his girlfriend with the ditziest Femi Benussi character ever conceived (and those familiar with her filmography will attest that that is a hard-won accolade) and b) is filmed in such a way as to give maximum exposure to the actress' vagina. The rape scene is filmed in a slightly more impressionistic style, with the actress' body reduced or confined to a series of close-ups, conveying a sense of the objectivity with which the killer views her. The killer character doesn't really gain anything from the scene, however-in fact, his opening few seconds of screen time, which shows him fondling the breast of a woman he's just killed, provides pretty much all the characterisation he gets. There's a bit of aural experimentation on a couple of occasions, with his deep, gutteral breathing foregrounded, but this backfires on the second occasion in particular, as he sounds like a zombie (apt, given he'd go on to be one in The Beyond) and walks with a particularly slow, zombie-like shuffle, which is certainly different, if not overly threatening.
In common with other famous killers like Michael Myers and Jason Vorhees, Schweik here displays a preternaturally accurate homing capability. After stealing a car himself so he can give chase to the lovers who've pinched his, he unerringly sets off hot on their trail, despite the fact that they could presumable have taken an almost infinite number of routes. The pursuit does create some tension, and adds a general sense of foreboding and impending doom to the lovers' scenes, but not enough happens in the middle third of the movie. In fact, I'd argue that you could remove a 40 minute or so block from the middle of the film without losing much. You'd miss out on the classic police-stopping-the-car-with-the-corpse bit, which does have a bit of a spin here because the lovers aren't actually aware that there's a corpse in their boot, but owing to the scene's placement in the film, it's pretty obvious what the outcome will be. In fact, the frequency with which the corpse is almost discovered means that any tension inherent in the scenario so wrung out that there's no tension remaining in the scenario after a while.
One final point on Schweik's automobile pursuit-he seems to get up to all sorts of off-screen shenanigans. How else could you explain the fact that he's a mere few minutes behind the lovers as he passes through a garage, after which they're stopped by the police, only for him to then be half an hour behind them when they pass through a toll booth? (And the manner in which the toll booth scenes are shot tells you all you need to know about the paucity of budget; why build a fake booth when you can covertly film cars driving up to a real booth, then freeze-frame the action and have a conversation play out in voice over?) He then rocks up to the seaside resort seemingly hours after the kids' arrival. What's he been up to? And how the hell did he know where to go, at any point? This is a rare example of a film which would be far more plausible if it happened in the twenty first century of GPS tracking and mobile technology.
The seaside location seems fairly nice, although Cozzi doesn't go in for the sort of establishing shots which were used in sister seaside giallo Sister of Ursula and Eye of the Labyrinth to provide the illusion of a larger budget (to be fair, after the toll booth scene, he's not going to fool anyone into thinking that it's not an extremely cheap production). What little budget there was must have all gone into the absolute batshit insane production design of Giorgio Hiltonio's house, which is literally the gialloiest house ever (it's very, very, very yellow, you see). Painting Giorgio's sideburns grey must have cost a few bob too, I suppose.
It's hard to get away from the fact that The Killer Must Kill Again is a film with a fairly large moral vacuum at the centre. When a car-stealing philanderer is your most sympathetic male character, you know you're dealing with an extra-special group of assholes. There's absolutely no need to populate a film with sympathetic characters-I'd much rather watch interesting people than good people-but the film arguably shares the moral failings of its characters, having as it does the centrepiece of the rape scene (and portraying as it does a woman as moronic as Benussi's character). It's not excessively stylish, it's not fast-paced or exciting. It's not overly-good, really. So there you go.