In response to David Cronenberg's film, A Dangerous Method, this paper elucidates the erotic transference that was enacted in the analytic relationship between Carl Jung and Sabina Spielrein. Given that psychoanalysis was in its infancy, the blurring of boundaries in the analytic relationship at this time was common. What we would now consider boundary violations also led to a deeper understanding of transference and counter-transference dynamics and provided vital lessons for future training. The erotic transference between Jung and Spielrein manifested the mutual idolisation that both had experienced at the hands of their mothers and the sadomasochistic attachment that had evolved from their early relationships. There is no evidence that Spielrein's powerful erotic transference was ever worked through. Despite this, and amidst other struggles in her life, Spielrein made significant contributions to both Jung and Freud's thinking and was one of the first pioneers of child analysis.