We present FERARI, a prototype for processing voluminous event streams over multi-cloud platforms. At its core, FERARI both exploits the potential for in-situ (intra-cloud) processing and orchestrates inter-cloud complex event detection in a communicationefficient way. At the application level, it includes a user-friendly query authoring tool and an analytics dashboard providing granular reports about detected events. In that, FERARI constitutes, to our knowledge, the first complete end-to-end solution of its kind. In this demo, we apply the FERARI approach on a real scenario from the telecommunication domain.