CST_ Netflix presents a film directed by Simon Stone and written by Moira Buffini, based on the novel by John Preston. Rated PG-13 (for brief sensuality and partial nudity). Running time: 112 minutes. Opens Friday at Landmark Century Centre and on Netflix. Based on a 2007 novel by John Preston that was inspired by the incredible true story of one of the most significant British archaeological finds ever, “The Dig” maintains a dignified and restrained approach, even when the material gets a little salacious in the form of not one but two “forbidden” romances. Melodramatic relationship developments aside, this is primarily about the well-off widow Edith Pretty (Mulligan) and the skilled but relatively unschooled excavator and amateur archaeologist Basil Brown (Ralph Fiennes), who in 1939 is hired by Edith to poke around the mounds of earth on the property of her house at Sutton Hoo. (Stories had been circulating for years about potential treasure buried beneath the land.)