highly recommonded , this movie is not for everyone but those who've experienced some life and interested in human characters . this movie has very cynical view on the humanity even from the begining through Dr.ritter's self dialogue , if you have a couple on limited resource , they'll last ; if we introduce another couple , then there is competition and struggle for resources ; if we introduce 3rd couple , then we have greatly increased the odds that newly joined human being is narcissistic psychopath , but since no one is bound by any laws of rules , how to constrain such parasitic member of the community , by become a murder...