Theatre and improvisation have spent over a century developing systematic approaches to presence, narrative, empathy, and collaborative sense-making under uncertainty. These are the same capacities that service design demands of its practitioners, and that conventional design training struggles to cultivate. Despite structural parallels identified in the literature, no empirical study has examined how service design practitioners specifically experience theatre-based training, or whether and how it transfers into their professional practice.This study addresses that gap through a practice-led qualitative case study organised around a two-day Storytelling in Service Design workshop, conducted in December 2024 with fourteen first-year students of an Erasmus Mundus joint master's programme. Data was collected across four phases: a pre-workshop survey, facilitator field notes, a post-workshop survey, and six in-depth follow-up interviews conducted approximately three months after the workshop. Analysis followed Braun and Clarke's (2006) thematic analysis framework.The findings identify six themes. Embodied activity was the primary entry point to learning. A group storytelling exercise restructured the social conditions of the room and enabled everything that followed. Two narrative frameworks transferred with durability into professional practice, in both cases because they arrived after embodied encounter rather than before it. Most significantly, several participants independently generated narrative tools from internalised storytelling principles rather than applying what they had been taught, a form of cognitive reorientation that represents the study's deepest evidence of transfer. Shared vulnerability was the mechanism of learning rather than an obstacle to it. Transfer was real but uneven, shaped by timing, design gaps, and the absence of sustained practice opportunities.The study makes three contributions. It provides the first empirical account of service design practitioners experiencing theatre-based training. It offers a differentiated transfer typology distinguishing direct application, indirect orientation shift, and structural constraint. And it generates actionable design insights for future workshop practice, including the primacy of practice-before-theory sequencing and the register mismatch between embodied and meditative learning modes. The study's scope is bounded by its single-workshop, single-cohort design, and its findings are offered as a carefully evidenced opening of terrain rather than a claim to generalisability.