Jean Laplanche's interest in psychosis dates back to at least the early 1960s, that is to say, the period of his cooperation with Lacan. As Laplanche's thought developed towards the general theory of seduction, which was his most significant theoretical achievement, the conceptualization of the etiology and symptomatology of psychosis became increasingly complex. The paper aims to present crucial elements of the Laplanchian theory of psychosis, such as the role of sexual reality and ego-agency, the concept of intromission and implantation, and finally the concept of the radical failure of translation. The last part of the article is devoted to the possibility of psychoanalytic or psychoanalysis-inspired treatment of psychosis. In addition, a modified topography model proposed by Laplanche is presented. A "Unified Theory of the Apparatus of the Soul"-as Laplanche calls his topography-is an attempt to reconcile the theory of psychosis with the general model of psychic apparatus.