On June 5, 1989, one day after the Chinese military cleared Tiananmen Square, a man in a white shirt holding two shopping bags stepped in front of a column of Type 59 tanks on Chang'an Avenue. He shifted left and right to block the lead tank, climbed onto its hull to speak with the crew, and was then pulled away by two figures in blue. This episode reconstructs those few minutes and asks how someone who appears on Time magazine's list of the century's most influential people could vanish without a trace.

The conversation covers the psychology of why the tanks stopped, the improvised smuggling operation that got the photographs out of the Beijing Hotel, and the contradictory theories about who Tank Man was and what became of him.

• How AP photographer Jeff Widener got the shot with film supplied by student Kirk Martsen, and how Char ...