Documentary director Andrea Luka Zimmerman embeds herself with Bo Gritz, the Special Forces veteran whose bloodthirsty real-life exploits inspired Rambo and others. As the alleged real-life inspiration for Sylvester Stallone’s Rambo character, Marlon Brando’s Colonel Kurtz in Apocalypse Now , and George Peppard’s “Hannibal” Smith in The A-Team , James Gordon “Bo” Gritz should should have provided rich material for an engrossing documentary.