As a teenager in the '80s, I remember the POW/MIA flags and the chest-thumping jingoism of Rambo, swooping in to rescue languishing and forgotten American prisoners from their barbaric captors. It all left me with a sense that maybe there actually were US servicemen still in captivity more than 20 years after the end of the war. When was the last POW recovered alive? Is there any evidence to suggest there were others kept longer?