Big data and cybercrime are creating 'upstream', big data related cyber-dependent crimes such as data breaches. They are essential components in a cybercrime chain which forms a cybercrime ecosystem that cascades 'downstream' to give rise to further crimes, such as fraud, extortion, etc., where the data is subsequently monetized. These downstream crimes have a massive impact upon victims and data subjects. The upstream and downstream crimes are often committed by entirely different offending actors against different victim groups, which complicates and frustrates the reporting, recording, investigative and prosecution processes. Taken together the crime stream's cascade effect creates unprecedented societal challenges that need addressing in the face of the advances of AI and the IoT. This phenomenon is explored here by unpacking the TalkTalk case study to conceptualize how big data and cloud computing are creating cascading effects of disorganized, distributed and escalating data crime. As part of the larger CRITiCal project, the paper also hypothesizes key factors triggering the cascade effect and suggests a methodology to further investigate and understand it.