Facebook CEO Mark Zuckerberg is back in Washington this week arguing for libra, the digital currency his company created.

This, after he last week made the case in front of an audience at Georgetown University that Facebook's future, its past and its reason for being are all tied up in free speech.

So, what's at stake for the company?

Jon Fortt sits down with The New York Times' Farhad Manjoo and John Stanton, co-founder of the Save Journalism Project, to discuss Zuckerberg's congressional testimony on Facebook's libra project.

Fortt Knox is a weekly podcast from CNBC anchor Jon Fortt. Previous episodes of the program can be found here.