"Hello, I'm Johnny Cash." We welcome Boyd Holbrook – who portrays Johnny Cash in Bob Dylan biopic A Complete Unknown – to Popcorn Podcast. A Complete Unknown tells the electric true story behind the rise of one of the most iconic singer-songwriters in history, Bob Dylan. Within that story is the surprising relationship between Cash and Dylan. Holbrook shares what he discovered about the troubled musician through letters Cash wrote to Dylan, as well as why Holbrook calls Chalamet a "trained killer”…