"The Mueller Report: The Findings of the Special Counsel Investigation" by Robert S. Mueller III, Special Counsel's Office U.S. Department of Justice is one of the most important and consequential documents of the modern era. Thanks to Audible, as long as you have an Amazon account, you can listen to the report for free (all eighteen hours of it).
There is also an Audible version of the Mueller Report provided by the Washington Post that's available for purchase, and includes exclusive analysis by their Pulitzer Prize winning staff.
If you prefer to listen to the report on SoundCloud, it is also available there (thanks to Mike Schaefer for the link).
To read along, you can download a PDF version of the redacted report at the US Department of Justice website.