This article proposes a rereading of the “Rat Man” (Freud, 1915), to provide the clinician with a deeper understanding of the symptomatology of obsessional neurosis. Nowadays, obsessional neurosis has been set aside as a diagnostic and nosographic category, overshadowed by attention to personality disorders, borderline states, narcissistic perversion and, especially, psychopathology that is understood from the point of view of the DSM. However, it is nevertheless very present in our clinical practice. Its tortuous and complex symptomatology, with its infernal alternation between contradictory impulses, rumination, obsessions, omnipresent doubt, undoing, and the inability to reach a compromise can be confusing to the therapist. In their relentless attempt to reconcile the irreconcilable, these patients may quickly lose the clinician in the maze of their defences. By retracing the complex and sometimes opaque twists and turns of the Rat Man case history step by step, this article seeks to help the clinician grappling with transference, associations, and symptoms that are both typical and confusing.