In Lynn Shelton’s new comic caper film 'Sword of Trust,' Marc Maron plays a pawnbroker who gets caught up in a scheme to sell a Civil War artifact of dubious provenance. Shelton and Maron tell us about making the movie in 12 days in Alabama, and about shooting an extended, improvised, soul-baring monologue in the back of a sweltering box truck...for nine hours.