'''''[[Reazione a Catena]]''''' (also known as ''Bay Of Blood'', ''Twitch Of The Death Nerve'', ''Ecologia Del Delitto''...) is a 1971 horror film by Mario Bava. Designed as a comeback film after he lost his distribution deal with American International Pictures, Bava effectively created a film that has served as the blueprint for the Bodycount/Slasher genre of horror, with many of its sequences copied by other horror films (most notably ''[[Friday the 13th (film)|Friday Thethe 13th]]'')
The film's plot is a convoluted "[[Who Done ItDunnit|whodunnit]]", as people begin dying left and right during the course of a long weekend at the lakeside home of an elderly heiress. There are multiple murderers at work, as a slew of shady characters (and a quartet of sex-obsessed teens) end up dying in horrific fashion. There is also a [[SurpriseTwist Ending]] that will shock you...
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* [[Anyone Can Die]]: And does.
* [[Creepy Child]]: The {{spoiler|killers'}} kids.