At a time when most Wall Street firms had stopped doing business with Donald J. Trump, a single bank lent him more than $2 billion. We look at the two-decade relationship that could unlock the president’s financial secrets. Guests: Natalie Kitroeff, a business reporter for The New York Times, spoke with David Enrich, the finance editor and author of the forthcoming book “Dark Towers: The Inside Story of the World’s Most Destructive Bank.” For more information on today’s episode, visit nytimes.com/thedaily. Background reading: A real estate mogul made toxic by polarizing rhetoric and a pattern of defaults. A bank with longstanding financial problems and a record of misconduct. Read about President Trump’s tumultuous history with Deutsche Bank.A federal judge on Wednesday ruled against a request from the president to block Deutsche Bank from complying with congressional subpoenas.