Sometimes a single step is our salvation. On Thanksgiving Day in 1944, a young American platoon sergeant named Mac St. Johns led his men on a scouting mission in the French countryside. They were looking for German soldiers known to be in the area. Heading toward a crossroads under the faint light of dawn, Mac “stood stark still” and argued with himself about what to do next. He knew that he should have his men “fan out so that they could move with the cover of the trees” in the surrounding forest. But a voice in his head told him...