This is the back story to the collapse of the largest Bitcoin exchange of its time: Mt. Gox, and the person running the exchange at the time, Mark Karpeles. When Mark took over the exchange from jed McCaleb in 2011 it was one of the earliest exchanges available and Bitcoin was worth only around $1.20.
Because of the interest in the Silk Road site where illegal drugs could be purchased for Bitcoin (only) the price soon dramatically increased. It also increased when WikiLeaks funding was blocked and during the Cyprus banking crisis, and was soon worth over $1,000.
The Bitcoins were being stored in offline cold wallets which no one was keeping an eye on. At some point it became clear that hundreds of thousands of Bitcoins were missing, and Mt. Gox was simply unable to meet withdrawal requests, which eventually led to a filing for bankruptcy in the Japanese and USA courts.
Besides narrating the story, the film features a long interview with Mark, and many other interviews with former employees, early supporters of Bitcoin, his mother, investigators and others involved in the case. It seems to be the case that the Bitcoins were being slowly syphoned off during the whole period of its operation.
This remarkable story is well told in this film, which is one of the better films of its type. I find the story intriguing and not at all as clear cut as it appears at first glance. It is unclear if we will ever know the whole story, and even most of it, as it is not at all clear anyone actually does know it, at least not as yet.