In the 1930s, Japan’s notorious Unit 731 carried out brutal experiments on the population of recently-invaded Manchuria. Whole villages and towns were deliberately infected with plague, and sufferers were dissected alive.

Prisoners of war were shot and operated on without anaesthetic so army doctors could practise field surgery. In World War II Germany, concentration camp doctors like Josef Mengele selected twins and Romany prisoners for obscure medical experiments, and killed enemy prisoners in low temperature or high altitude tests, supposedly to protect their own sailors and airmen.

After the war, many Nazi ‘Doctors of Death’ were brought to justice. But in Japan the head of Unit 731 cut a deal with US intelligence; the Americans knew they could never replicate biological data gained through experiments on humans. There are suggestions the US used Japanese bio-weapons in the Korean War — but America began to suspect the North Koreans had their own unorthodox methods: brainwashing US prisoners with drugs.

It was the start of a chemical arms race, reaching its peak in the 1960s and ’70s with LSD as the mind-control secret weapon of both sides, intended to cripple the enemy without firing a shot. The US showed drugs experiments in army-sponsored TV documentaries, while in Czechoslovakia — the drugs laboratory for the whole Eastern Bloc – the state-controlled movie industry was enrolled to shoot surreal feature films portraying the drugs experience.

Besides biological and chemical weapons, both Americans and Soviets routinely exposed their own soldiers to nuclear fallout in A-bomb tests. According to General Jan Sejna, the highest-ranking military defector from the East, the Soviets even tied living prisoners of war to stakes as human guinea-pigs in their nuclear tests.

The film has a moving and shocking interview with a Japanese doctor who operated on unanaesthetised prisoners. A captured US pilot is seen making an apparently false confession in Korea. A Czech military chemist explains how chemical weapons are deployed, and a victim of a drug-fuelled interrogation describes the experience. The man who debriefed Czech defector Jan Sejna describes the terrifying network of experimentation behind chemical, biological and atomic weapons. The Cold War is over, but weapons development — and testing — continues.