Today’s issue of The Guardian has a long and fascinating article by Luke Harding that gives a biography of Edward Snowden, tracing his life story and how his views changed over time from being a loyal CIA operative to the point where he felt that he had to leak all the NSA and GCHQ documents.

It is an absolutely fascinating story of a shift in his views from where he roundly condemned leakers of confidential documents to deciding to become one of the biggest leakers of all time, and how he systematically set about collecting the documents that he felt the public should see and deciding how and to whom they should be released.

One passage that gets at his motives is from his first meeting with Glenn Greenwald, Laura Poitras, and Ewen MacAskill in Hong Kong

The NSA could bug “anyone”, from the president downwards, he said. In theory, the spy agency was supposed to collect only “signals intelligence” on foreign targets. In practice this was a joke, Snowden told Greenwald: it was already hoovering up metadata from millions of Americans. Phone records, email headers, subject lines, seized without acknowledgment or consent. From this you could construct a complete electronic narrative of an individual’s life: their friends, lovers, joys, sorrows.

The NSA had secretly attached intercepts to the undersea fibre optic cables that ringed the world. This allowed them to read much of the globe’s communications. Secret courts were compelling telecoms providers to hand over data. What’s more, pretty much all of Silicon Valley was involved with the NSA, Snowden said – Google, Microsoft, Facebook, even Steve Jobs’s Apple. The NSA claimed it had “direct access” to the tech giants’ servers. It had even put secret back doors into online encryption software – used to make secure bank payments – weakening the system for everybody. The spy agencies had hijacked the internet. Snowden told Greenwald he didn’t want to live in a world “where everything that I say, everything that I do, everyone I talk to, every expression of love or friendship is recorded”.

Snowden agreed to meet MacAskill the next morning. The encounter went smoothly until the reporter produced his iPhone. He asked Snowden if he minded if he taped their interview, and perhaps took some photos? Snowden flung up his arms in alarm, as if prodded by an electric stick. “I might as well have invited the NSA into his bedroom,” MacAskill says. The young technician explained that the spy agency was capable of turning a mobile phone into a microphone and tracking device; bringing it into the room was an elementary mistake. MacAskill dumped the phone.

Snowden’s own precautions were remarkable. He piled pillows up against the door to stop anyone eavesdropping from outside in the corridor. When putting passwords into computers, he placed a big red hood over his head and laptop, so the passwords couldn’t be picked up by hidden cameras. On the three occasions he left his room, Snowden put a glass of water behind the door next to a bit of tissue paper. The paper had a soy sauce mark with a distinctive pattern. If anyone entered the room, the water would fall on the paper and it would change the pattern.

MacAskill asked Snowden, almost as an afterthought, whether there was a UK role in this mass data collection. It didn’t seem likely to him. MacAskill knew that GCHQ had a longstanding intelligence-sharing relationship with the US, but he was taken aback by Snowden’s vehement response. “GCHQ is worse than the NSA,” Snowden said. “It’s even more intrusive.”

When the Guardian’s New York editor Janine Gibson told the US government about the first article they were planning to print, they sent a high-powered team to her office to try and bully her into delaying publishing but failed. The article tells what happened right after.

That evening, diggers arrived and tore up the sidewalk immediately in front of the Guardian’s US office, a mysterious activity for a Wednesday night. With smooth efficiency, they replaced it. More diggers arrived outside Gibson’s home in Brooklyn. Soon, every member of the Snowden team was able to recount similar unusual moments: “taxi drivers” who didn’t know the way or the fare; “window cleaners” who lingered next to the editor’s office. “Very quickly, we had to get better at spycraft,” Gibson says.

It is a fascinating account. It is a long article but well worth reading in full. It has all the makings of becoming a major film some day.