Virtual Reality (VR) narratives have the unprecedented potential to connect with an audience through presence, placing viewers within the narrative. The onset of consumer VR has resulted in an explosion of interest in immersive storytelling. Planning narratives for VR, however, is a grand challenge due to its unique affordances, its evolving cinematic vocabulary, and most importantly the lack of supporting tools to explore the creative process in VR. In this paper, we distill key considerations with the planning process for VR stories, collected through a formative study conducted with film industry professionals. Based on these insights we propose a workflow, specific to the needs of professionals creating storyboards for VR film, and present a multi-device (tablet and head-mounted display) sto-ryboard tool supporting this workflow. We discuss our design and report on feedback received from interviews following demonstration of our tool to VR film professionals.