Andrew Weissmann, a lead prosecutor in the Mueller investigation, shares his experience with the probe and its report on Russian interference in the 2016 election. Weissmann says the constant threat that President Trump might fire Mueller and shut down the probe and the prospect of Trump granting pardons to key witnesses had an effect on Mueller and his team. Weissman believes Mueller was timid when he should have been aggressive in getting information and testimony, and he says the final report should have been far clearer in its conclusions about the president's conduct. His book, 'Where Law Ends,' takes us inside the 22-month investigation. Also, book critic Maureen Corrigan reviews the novel 'Leave the World Behind,' by Rumaan Alam, which she calls a signature read for 2020.