In the new novel “A Door in the Earth,” journalist-turned-author Amy Waldman takes an unspearing look at the do-gooder narrative. Her story follows Parveen Shams, a young Afghan American woman from the Bay Area. After graduating from Berkeley, Parveen heads to Afghanistan. It’s 10 years into the U.S. war there. She plans to work at a maternity clinic run by Gideon Crane, a humanitarian and the author of a best-selling memoir. But within days of getting to the clinic, Crane’s story and Parveen’s own idealism begin to fall apart.