Audio Guides have been the prevalent mode of information delivery in public spaces such as Museums and Art Galleries. These devices are programmed to render static information to their users about the collections and artworks present and require human input to operate. The inability to automatically deliver contextual messages and the lack of interactivity are major hurdles to ensuring a rich and seamless user experience. Ubiquitous smartphones can be leveraged to create pervasive audio guides that provide rich and personalized user experience. In this paper, we present the design and implementation of "Usher", an intelligent tour companion. Usher provides three distinct advantages over traditional audio guides. First, Usher uses smartphone sensors to infer user context such as his physical location, locomotive state and orientation to deliver relevant information to the user. Second, Usher also provides interface to a cognitive Question Answer(QA) service for the inquisitive users and answers contextual queries. Finally, Usher notifies users if any of their social media friends are present in the vicinity. The ability to seamlessly track user context to provide rich semantic information and the cognitive capability to answer contextual queries means that Usher can enhance the user experience in a museum by multitudes.