Glenn Simpson has a lot to say about business corruption and Russian influence in the U.S. In this episode, we speak to him. Simpson first came to these issues as an investigative journalist at The Wall Street Journal. In 2010, he co-founded Fusion GPS, a research firm. During the 2016 campaign, he began to research Donald Trump for two clients: first for a Republican opposed to Trump and then for a lawyer for Democrats.

Fusion is most famous — or infamous — for hiring Christopher Steele, the former British spy who wrote the so-called Steele dossier. We asked Simpson about the dossier, about becoming a part of the story, and about the deposition of former national security aide Fiona Hill, who said that when it comes to Russia, "corruption is our Achilles heel."

Simpson is now the author, with Peter Fritsch, of the new book, "Crime in Progress: Inside the Steele Dossier and the Fusion GPS Investigation of Donald Trump."