When Beto O'Rourke granted filmmaker David Modigliani behind-the-scenes access for his run to unseat Ted Cruz, Modigliani turned to Texas music legend David Garza to create - and perform - the original score for the upcoming HBO documentary at engineer David Boyle's studio inside an old Baptist church in Austin. How do directors and composers best communicate to build an interwoven story - from scene to soundtrack? The three Davids share the unique process behind their year-long collaboration.

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