In the shadowy world of commercial spyware, the Quadream group has devised a potent tool known as REIGN. Your task is to investigate a series of cyber incidents where REIGN has been deployed against iOS devices, utilizing sophisticated zero-click iCloud calendar exploits. As an intermediate analyst, you'll uncover the methods of operation, tracing the spyware's journey from initial access to data exfiltration, and unravel the web of government clients behind its deployment.