On one level, the saga of Madame Giselle is a story about, in no particular order, allegations by two neighbors who say they were swindled in an elaborate scheme to sell T-shirts to the Venezuelan army, a cash-stuffed envelope slipped under a doorway, a legendary bygone scandal involving the Colombian military and a glamorous woman known as “The Blonde,” an ongoing multimillion-dollar Colombian fraud case, and a supposed helicopter ride into Syria. But on another level, as illustrated in interviews and in hundreds of text messages obtained by The Washington Post, it’s a story about friendship and trust, about what...