The development of nuclear weapons in the 20th century changed the world like no other scientific event. During WWII, U.S. spies in Europe found Germany’s nuclear secrets buried under a cesspit. The Nazis hadn’t been a serious threat, but the cooperation of spies and scientists had delivered results elsewhere.

The Soviets’ first test came in 1949 — when the best U.S. intelligence had estimated 1953. China was next, testing its first bomb in 1964 and even firing a nuclear missile into its interior in 1966. India, Taiwan, Israel, South Africa and Pakistan followed. France was busiest, however. It tested 210 bombs before stopping in 1996. And if you don’t think Iraq ever had a go, think again. By 1990, the suspected weapons facility of Tarmiya complex in Iraq consisted of 400 buildings.

Every nation that moved to join the nuclear club presented new problems for U.S. spies. Methods to detect tests included long-range aircraft mounted with filters to catch radioactive debris, a network of stations to measure seismic waves and satellites that would eject film capsules to be caught mid-air by planes.

Some mysteries remain, such as: what was the double flash detected by a Vela satellite over South Africa in 1979? It wasn’t the South Africans; they weren’t ready to test. Was it an Israeli device?

Richelson’s book is deeply researched and sometimes laboured, but stick with it because the focus shifts constantly from friend to pariah, dictator to defector, super spy to red herring. Unfortunately it also feels as though the author assumes the reader has a working knowledge of how bombs are made and how they work; a section with diagrams and simple plant schematics would have been helpful.