Unit 731, known as 'Asia's Auschwitz', was Japan’s most secretive World War II programme – a covert facility based in Harbin, China, responsible for human experimentation and biological warfare research on a devastating scale.

This ground-breaking investigation reveals the horrifying extent of the unit's crimes, which have been covered up for decades. Rare access to the last surviving unit member, Hideo Shimizu, as well as testimony from other survivors and newly declassified archives reveal the shocking scale of harm inflicted on Chinese, British and American victims. Between 1936-1945, around 14,000 prisoners were killed within the facility, and up to 500,000 civilians across China were killed as a result of the Unit's biological weapons research.

For the first time, this series reveals the secret post-war deal with the USA which hid these atrocities, and uncovers how key Unit 731 members were granted immunity in a political cover-up which continues to haunt families across the world today.