The secretive Catholic sect Opus Dei seems to be popping up everywhere. But what is it? Many people are familiar with it from depictions in fiction like "The Davinci Code," but the reality is both more mundane and in many ways, more sinister.

Dave is joined by financial journalist Gareth Gore, who got into the story by covering the failure of Spanish bank Banco Popular. He found that the bank led to a rabbit hole — and in the center of it was Opus Dei. Part classic authoritarian mind control cult, part spiritual organization, part fraud, and part geopolitical powerhouse, Gore's new book "Opus: The Cult of Dark Money, Human Trafficking, and Right-Wing Conspiracy inside the Catholic Church" is a page-turning account of one of the most influential groups in the last 100 years.