How Jehovah's Witnesses have helped shape history beyond the doorstep.

They are moral conservatives who stay out of politics, but they won a record number of court cases, expanding freedom for everyone. They refuse blood transfusions on religious grounds, but they embrace the science behind bloodless surgery. In Nazi Germany, they could fight for Hitler or go to the concentration camps. They chose the camps. Following two families who stand firm in their controversial and misunderstood Christian faith, "Knocking" reveals how Jehovah's Witnesses have helped shape history beyond the doorstep. By Joel P. Engardio and Tom Shepard.